Comparative chromosome mapping of repetitive sequences. Implications for genomic evolution in the fish, Hoplias malabaricus

<p>Abstract</p> <p>Background</p> <p>Seven karyomorphs of the fish, <it>Hoplias malabaricus </it>(A-G) were previously included in two major groups, Group I (A, B, C, D) and Group II (E, F, G), based on their similar karyotype structure. In this paper, karyomorphs from Group I were analyzed by means of distinct chromosomal markers, including silver-stained nucleolar organizer regions (Ag-NORs) and chromosomal location of repetitive sequences (18S and 5S rDNA, and satellite 5S<it>Hind</it>III-DNA), through fluorescence in situ hybridization (FISH), in order to evaluate the evolutionary relationships among them.</p> <p>Results</p> <p>The results showed that several chromosomal markers had conserved location in the four karyomorphs. In addition, some other markers were only conserved in corresponding chromosomes of karyomorphs A-B and C-D. These data therefore reinforced and confirmed the proposed grouping of karyomorphs A-D in Group I and highlight a closer relationship between karyomorphs A-B and C-D. Moreover, the mapping pattern of some markers on some autosomes and on the chromosomes of the XY and X₁X₂Y systems provided new evidence concerning the possible origin of the sex chromosomes.</p> <p>Conclusion</p> <p>The <it>in situ </it>investigation of repetitive DNA sequences adds new informative characters useful in comparative genomics at chromosomal level and provides insights into the evolutionary relationships among <it>Hoplias malabaricus </it>karyomorphs.</p

Chromosome spreading of associated transposable elements and ribosomal DNA in the fish Erythrinus erythrinus. Implications for genome change and karyoevolution in fish

<p>Abstract</p> <p>Background</p> <p>The fish, <it>Erythrinus erythrinus</it>, shows an interpopulation diversity, with four karyomorphs differing by chromosomal number, chromosomal morphology and heteromorphic sex chromosomes. Karyomorph A has a diploid number of 2n = 54 and does not have differentiated sex chromosomes. Karyomorph D has 2n = 52 chromosomes in females and 2n = 51 in males, and it is most likely derived from karyomorph A by the differentiation of a multiple X₁X₂Y sex chromosome system. In this study, we analyzed karyomorphs A and D by means of cytogenetic approaches to evaluate their evolutionary relationship.</p> <p>Results</p> <p>Conspicuous differences in the distribution of the 5S rDNA and <it>Rex3 </it>non-LTR retrotransposon were found between the two karyomorphs, while no changes in the heterochromatin and 18S rDNA patterns were found between them. <it>Rex3 </it>was interstitially dispersed in most chromosomes. It had a compartmentalized distribution in the centromeric regions of only two acrocentric chromosomes in karyomorph A. In comparison, in karyomorph D, <it>Rex3 </it>was found in 22 acrocentric chromosomes in females and 21 in males. All 5S rDNA sites co-localized with <it>Rex3</it>, suggesting that these are associated in the genome. In addition, the origin of the large metacentric Y chromosome in karyomorph D by centric fusion was highlighted by the presence of internal telomeric sites and 5S rDNA/<it>Rex3 </it>sites on this chromosome.</p> <p>Conclusion</p> <p>We demonstrated that some repetitive DNAs (5S rDNA, <it>Rex3 </it>retroelement and (TTAGGG)_ntelomeric repeats) were crucial for the evolutionary divergence inside <it>E. erythrinus</it>. These elements were strongly associated with the karyomorphic evolution of this species. Our results indicate that chromosomal rearrangements and genomic modifications were significant events during the course of evolution of this fish. We detected centric fusions that were associated with the differentiation of the multiple sex chromosomes in karyomorph D, as well as a surprising increase of associated 5S rDNA/<it>Rex3 </it>loci, in contrast to karyomorph A. In this sense, <it>E. erythrinus </it>emerges as an excellent model system for better understanding the evolutionary mechanisms underlying the huge genome diversity in fish. This organism can also contribute to understanding vertebrate genome evolution as a whole.</p

Defining the True Sensitivity of Culture for the Diagnosis of Melioidosis Using Bayesian Latent Class Models

BACKGROUND: Culture remains the diagnostic gold standard for many bacterial infections, and the method against which other tests are often evaluated. Specificity of culture is 100% if the pathogenic organism is not found in healthy subjects, but the sensitivity of culture is more difficult to determine and may be low. Here, we apply Bayesian latent class models (LCMs) to data from patients with a single Gram-negative bacterial infection and define the true sensitivity of culture together with the impact of misclassification by culture on the reported accuracy of alternative diagnostic tests. METHODS/PRINCIPAL FINDINGS: Data from published studies describing the application of five diagnostic tests (culture and four serological tests) to a patient cohort with suspected melioidosis were re-analysed using several Bayesian LCMs. Sensitivities, specificities, and positive and negative predictive values (PPVs and NPVs) were calculated. Of 320 patients with suspected melioidosis, 119 (37%) had culture confirmed melioidosis. Using the final model (Bayesian LCM with conditional dependence between serological tests), the sensitivity of culture was estimated to be 60.2%. Prediction accuracy of the final model was assessed using a classification tool to grade patients according to the likelihood of melioidosis, which indicated that an estimated disease prevalence of 61.6% was credible. Estimates of sensitivities, specificities, PPVs and NPVs of four serological tests were significantly different from previously published values in which culture was used as the gold standard. CONCLUSIONS/SIGNIFICANCE: Culture has low sensitivity and low NPV for the diagnosis of melioidosis and is an imperfect gold standard against which to evaluate alternative tests. Models should be used to support the evaluation of diagnostic tests with an imperfect gold standard. It is likely that the poor sensitivity/specificity of culture is not specific for melioidosis, but rather a generic problem for many bacterial and fungal infections

Effectiveness of Oral Nutritional Supplementation for Older Women after a Fracture: Rationale, Design and Study of the Feasibility of a Randomized Controlled Study

<p>Abstract</p> <p>Background</p> <p>Malnutrition is a problem for many older people recovering from a hip and other major fractures. Oral supplementation with high calorie high protein nutrients is a simple intervention that may help older people with fractures to improve their recovery in terms of rehabilitation time, length of hospital stay and mortality. This paper reports a pilot study to test the feasibility of a trial initiated in a hospital setting with an oral supplement to older people with recent fractures.</p> <p>Method</p> <p>A randomized controlled trial with 44 undernourished participants admitted to a hospital following a fracture. The intervention group (n = 23) received a high calorie high protein supplement for forty days in addition to their diet of choice. The control group (n = 21) received high protein milk during their hospital stay in addition to their diet of choice and their usual diet when discharged from hospital.</p> <p>Results</p> <p>All participants were women and their mean age was 85.3 (± 6.1) years. Twenty nine (65%) participants had a hip fracture. At baseline no differences were measured between the two groups regarding their nutritional status, their cognitive ability or their abilities in activities of daily living. There were no significant differences between the intervention and control group with reference to nutritional or functional parameters at 40 day and 4 month follow-ups. Median length of stay in hospital was 18.0 days, with 12 participants being readmitted for a median of 7.0 days.</p> <p>Conclusion</p> <p>It is feasible to perform a randomised trial in a hospital and community setting to test the effect of an oral high energy high protein supplement for older people. Due to the limited number of participants and incomplete adherence with use of the supplements no conclusion can be drawn about the efficacy or effectiveness of this intervention.</p

Brazilian obstetrician-gynecologists and abortion: a survey of knowledge, opinions and practices

BACKGROUND: Abortion laws are extremely restrictive in Brazil. The knowledge, opinions of abortion laws, and abortion practices of obstetrician-gynecologists can have a significant impact on women's access to safe abortion. METHODS: We conducted a mail-in survey with a 10% random sample of obstetrician-gynecologists affiliated with the Brazilian Federation of Obstetricians and Gynecologists. We documented participants' experiences performing abortion under a range of legal and illegal circumstances, and asked about which abortion techniques they had experience with. We used chi-square tests and crude logistic regression models to determine which sociodemographic, knowledge-related, or practice-related variables were associated with physician opinion. RESULTS: Of the 1,500 questionnaires that we mailed out, we received responses from 572 (38%). Less than half (48%) of the respondents reported accurate knowledge about abortion law and 77% thought that the law should be more liberal. One-third of respondents reported having previous experience performing an abortion, and very few of these physicians reported having experience with manual vacuum aspiration (MVA) or with misoprostol with either mifepristone or methotrexate. Physicians that favored liberalization of the law were more likely to have correct knowledge about abortion law, and to be in favor of public funding for abortion services. CONCLUSION: Brazilian obstetrician-gynecologists need more information on abortion laws and on safe, effective abortion procedures

Chagas disease: an impediment in achieving the Millennium Development Goals in Latin America

<p>Abstract</p> <p>Background</p> <p>Achieving sustainable economic and social growth through advances in health is crucial in Latin America within the framework of the United Nations Millennium Development Goals.</p> <p>Discussion</p> <p>Health-related Millennium Development Goals need to incorporate a multidimensional approach addressing the specific epidemiologic profile for each region of the globe. In this regard, addressing the cycle of destitution and suffering associated with infection with <it>Trypanosoma cruzi</it>, the causal agent of Chagas disease of American trypanosomiasis, will play a key role to enable the most impoverished populations in Latin America the opportunity to achieve their full potential. Most cases of Chagas disease occur among forgotten populations because these diseases persist exclusively in the poorest and the most marginalized communities in Latin America.</p> <p>Summary</p> <p>Addressing the cycle of destitution and suffering associated with <it>T. cruzi </it>infection will contribute to improve the health of the most impoverished populations in Latin America and will ultimately grant them with the opportunity to achieve their full economic potential.</p

The combined use of Er,Cr:YSGG laser and fluoride to prevent root dentin demineralization

The use of erbium lasers to prevent caries in enamel has shown positive results. However, it is not known if Er,Cr:YSGG laser can also be used to increase acid resistance of root dentine, which is another dental tissue susceptible to the action of cariogenic bacteria. Objective: To analyze the effects of the Er,Cr:YSGG laser (λ=2.78 μm, 20 Hz) irradiation associated with 2% neutral sodium fluoride (NaF) to prevent root dentin demineralization. Material and Methods: One hundred human root dentin samples were divided into 10 groups (G) and treated as follows: G1: no treatment; G2: NaF; G3: laser (4.64 J/cm2) with water cooling (WC=5.4 mL/min); G4: laser (4.64 J/cm2) without WC; G5: laser (8.92 J/cm2) with WC; G6: laser (8.92 J/cm2) without WC; G7: laser (4.64 J/cm2) with WC and NaF; G8: laser (4.64 J/cm2) without WC and NaF; G9: laser (8.92 J/cm2) with WC and NaF; G10: laser (8.92 J/cm2) without WC and NaF. The NaF gel was applied alone or after 4 min of irradiation. After 14 days of acid challenge, the samples were sectioned and the Knoop microhardness (KHN) test was done at different depths (30, 60, 90 and 120 μm) from the outer dentin surface. Data were analyzed by one-way ANOVA and Fisher’s test (α=5%). Results: The results showed that G8 and G10 presented higher KHN than the G1 for the depths of 30 and 60 μm, indicating an increase of the acid resistance of the dentin in up to 35% (p<0.05). Conclusions: The use of Er,Cr:YSGG laser irradiation at 4.64 J/ cm2 and 8.92 J/cm2 without water cooling and associated with 2% NaF can increase the acid resistance of human root dentin