Thermoelectric transport properties of armchair graphene nanoribbon heterostructures.

In this paper, we numerically analyze the thermoelectric (TE) properties of recently synthesized graphene nanoribbon (GNR) heterostructures that are obtained as extensions of pristine armchair graphene nanoribbons (AGNRs). After simulating their band structure through a nearest-neighbor tight-binding model, we use the Landauer formalism to calculate the necessary TE coefficients, with which we obtain the electrical conductanceG, thermopowerS, thermal conductanceKe, linear-response thermocurrentIth/ΔT=GS, and figure of meritZT(using literature results for the phonon thermal conductanceKph), at room temperature. We then compare the results for the nanoribbon heterostructures with those for the pristine AGNR nanoribbons. The comparison shows that the metallic AGNRs become semiconducting (with much higherZTvalues) after the inclusion of the extensions that transform them into heterostructures and that some heterostructures have higher values ofZTwhen compared to the semiconducting pristine AGNRs from which they have originated.

Genetic profile of Brazilian patients with dystrophinopathies.

Different types of mutations in the DMD gene underlie Duchenne muscular dystrophies (DMD) and Becker muscular dystrophies (BMD). Large deletions and duplications are the most frequent causative genetic alterations worldwide, but little is known about DMD/BMD genetic profile in Brazil. Hence, we recruited patients with DMD and BMD from 8 neuromuscular reference centers along the country, and performed a comprehensive molecular investigation that included Multiplex Ligation-dependent Probe Amplification and Next generation sequencing (NGS) analyses. We evaluated 199 patients from 177 unrelated families: 166 with DMD, 32 with BMD and 1 1.5 years old asymptomatic patient with persistent hiperCKemia. Overall, large deletions (58.2%) followed by nonsense mutations (12.4%) and large duplications (11.3%) were the most frequent variants in Brazilian families. Large deletions were less frequent in BMD than in DMD (44.8% vs 60.8%). We identified 19 new DMD variants. Nonsense mutations were significantly more frequent in patients from northeastern region than from southern/southeastern regions of Brazil (27.7% vs 8.5%, P < .05). Genetic profile of Brazilian patients with DMD/BMD is similar to previously reported cohorts, but it is not uniform across the country. This information is important to plan rational clinical care for patients in face of the new coming mutation-specific therapies.

The role of sperm aneuploidy as a predictor of the success of intracytoplasmic sperm injection?

BACKGROUND: We present the first powered prospective study to assess whether sperm aneuploidy can predict the outcome of ICSI. METHODS: Our null hypothesis was that aneuploidy rates (AR) are identical in men who achieve successful (Group A) and unsuccessful (Group B) ICSI outcome. A power calculation yielded a sample number of 56 to achieve 80% power to reject our hypothesis at the 5% significance level. Samples for testing were obtained on the day of embryo transfer and tests were performed on raw pre-preparation samples. Sperm AR of chromosomes 13, 18, 21, X/Y were assessed using fluorescence in-situ hybridization (FISH) techniques (mean of 1223 sperm). RESULTS: There was no significant difference in any patient, seminal, cycle or laboratory characteristic between groups that may have affected outcome. Total AR (2.37 versus 1.18%, P = 0.01), as well as AR of chromosomes 18, X/Y and 18 + X/Y (1.48 versus 0.67%, P = 0.005) were significantly higher in Group B compared with Group A. Regression analysis confirmed these differences to be independent of other variables and showed a 2.6-fold change in odds of achieving a pregnancy for every 1% change in total AR. CONCLUSIONS: Our findings confirm a potential role for aneuploidy testing in the work-up of ICSI patients as a predictor of success, as well as in future genetic counselling. If confirmed, there may also be a place for a study of preimplantation genetic screening to improve ICSI success in men found to have high AR and ICSI failure.

The results of 154 ICSI cycles using surgically retrieved sperm from azoospermic men.

BACKGROUND: The effects of source of sperm, aetiology and sperm cryopreservation on ICSI cycles in azoospermic men were evaluated. The effect of aetiology of azoospermia on embryo development was also assessed. METHODS: This study was a retrospective analysis of 154 cycles (91 couples) using surgically retrieved sperm. Outcome measures were fertilization rate (FR), implantation rate (IR), and clinical pregnancy rate (CPR) and livebirth rate (LBR) per transfer. RESULTS: Our data demonstrated similar outcome between the use of epididymal or testicular sperm in men with obstructive azoospermic (OA). FR and IR were significantly lower (P < 0.05) using sperm from men with non-obstructive azoospermic (NOA), but although pregnancy outcome appeared lower, this did not reach statistical significance (P = 0.08). Cryopreservation of epididiymal sperm did not alter outcome, but the use of frozen-thawed testicular sperm did demonstrate a lower FR, with no statistical difference in IR or pregnancy outcome. Embryos derived from NOA sperm had impaired development beyond day 2 post-oocyte retrieval (OA, 44% <5 cell; NOA, 71% <5 cell; P = 0.002). CONCLUSIONS: The use of sperm from men with NOA significantly affects fertilization and implantation in ICSI cycles. The use of frozen-thawed testicular sperm affects fertilization rate without significantly altering pregnancy outcome. The use of such data on which to base clinical decisions needs to be supported by the meta-analyses of previous reports.

Genetic variation within the Merino sheep breed: analysis of closely related populations using microsatellites.

Genetic relationships among six populations of Merino sheep were investigated using microsatellites. The history of the six populations is relatively well documented, with all being derived from the Spanish Merino breed within the last 400 years. Genetic variation was highest amongst the Spanish and Portuguese populations, although the preservation of genetic diversity within the other populations was high. By a variety of different statistical tests the French Mutton, German Mutton and New Zealand Merino populations could be differentiated from each other and the Iberian Merinos, indicating that microsatellites are able to track relatively recent changes in the population structure of sheep breeds. The dendrograms constructed on the basis of microsatellite allelic frequencies showed that populations that have shared selection criteria (meat vs. wool) tend to cluster together.

Cytogenetic analysis of human preimplantation embryos following developmental arrest in vitro.

The relationship between chromosomal abnormalities in the human preimplantation embryo and developmental arrest in vitro was investigated. Cytogenetic analysis of 171 embryos that had arrested between the pronucleate and the 8-cell stages demonstrated that the overall incidence of chromosomal abnormality among these embryos was 63.4%. Of the embryos that arrested at the pronucleate stage (n = 48), 47.9% were chromosomally abnormal, compared with 59.5% of those that arrested between the 2- and 4-cell stages (n = 50), and 82.8% of those arrested between the 5- and 8-cell stage (n = 73). The rate of abnormality in embryos with poor morphology (irregular shaped blastomeres and considerable extracellular fragmentation) was significantly higher (86.8%; n = 33) than those with good morphology (60%; n = 51; P<0.005). These results suggest that there is an association between chromosomal abnormality, developmental arrest in vitro, and poor morphology.

The relationship between chromosomal abnormality in the human preimplantation embryo and development in vitro.

The relationship between the survival of the human preimplantation embryo in vitro and chromosomal abnormality was investigated by cytogenetic analysis of a total of 250 embryos of varying morphology between the pronucleate stage and the 8-cell stage. The overall incidence of chromosomal abnormality among these embryos was 49%. At the pronucleate stage (n = 46) the incidence was 65.2%, at the 2-4-cell stage (n = 126) it was 54.6%, and at the 5-8-cell stage (n = 78) it was 27.4%. Cleavage-stage embryos with poor morphology (irregular shaped blastomeres with severe extracellular fragmentation) showed a higher incidence of chromosomal abnormality (62%; 54 of 87 analysed) than those with good morphology (22.2%; 26 of 117 analysed). This study demonstrates: (i) that there is progressive loss of chromosomally-abnormal embryos during preimplantation development; and (ii) that there is an association between chromosomal abnormality and embryo morphology.

The effect of temperature fluctuations on the cytoskeletal organisation and chromosomal constitution of the human oocyte.

The effect of temperature fluctuation on spindle integrity and chromosomal organisation in the human oocyte, and the consequences of such effects on the chromosomal constitution of resulting parthenotes, were investigated. A total of 340 oocytes were stained immunocytochemically with an antibody to alpha-tubulin, and 502 were activated parthenogenetically. Exposure of oocytes to room temperature for 2, 10 or 30 min caused disruption of the spindle in 77% (n = 26), 72% (n = 18) and 89% (n = 19) of cases respectively, with evidence of chromosomal dispersal in 50%, 56% and 52.6% respectively. These effects were reversed when oocytes were returned to 37 degrees C after exposure to room temperature for 2 min, but not after 10 min or 30 min. Temperature reduction affected rates of parthenogenetic activation of oocytes (2 min: 67%, n = 27; 10 min: 68%, n = 28; 30 min: 54%, n = 35) and cleavage of resulting parthenotes, but only if oocytes were exposed to room temperature for 30 min (30 min: 53%, n = 19). There is a direct association between temperature-induced spindle damage in the oocyte (70%, 50 of 63) and chromosomal abnormalities in parthenotes developed from oocytes exposed to room temperature (56%, 23 of 41; p < 0.01).

[Heart surgery with extracorporeal circulation in pregnant women. Analysis of materno-fetal outcome]. / Cirurgia cardíaca com circulação extracorpórea em gestantes. Análise da evolução materno-fetal.

PURPOSE: To analyze maternal and fetal outcome in pregnant undergone to cardiac surgery. METHODS: We studied the evolution of 30 pregnant women submitted to cardiac surgery at the Hospital São Paulo, between Jan/81 and Dec/92 and, further, attended at this Hospital till the parturition. The following variables were analyzed: cardiopulmonary bypass, time of the procedure and time of the anoxia, patient temperature, surgical complications, and neonatal, maternal and fetal outcomes. RESULTS: All patients had rheumatic heart disease and, in 17, mitral stenosis was the main anatomic abnormality. Mitral commissurotomy was performed in 24 patients, double comissurotomy (mitral and aortic) in 1 patient and valve replacement was performed in 5. Cardiopulmonary bypass was utilized in all procedure; occurrence of surgical complications (p < 0.001) and the prolonged surgical time (p = 0.009) were related to the fetal mortality. There was 4 (13.3%) maternal deaths and 10 (33.3%) fetal deaths related to the surgery. CONCLUSION: The indication of cardiac surgery in pregnant women is heart failure, refractory to conventional therapy; cardiopulmonary bypass is associated with high fetal mortality.

The relationship between chromosomal abnormalities in the human oocyte and fertilization in vitro.

The relationship between chromosomal abnormalities in the human oocyte and fertilization in vitro was investigated by cytogenetic analysis of an unselected population of oocytes, where failure to achieve fertilization was attributed to dysfunctional spermatozoa. The results demonstrated that 47% of such oocytes were chromosomally abnormal. These data were used to calculate that the incidence of chromosomal abnormalities in oocytes that do, and those that do not develop pronuclei following insemination in vitro is 26.6% and 20.4% respectively. Statistical analysis demonstrated no relationship between chromosomal abnormality in the oocyte and its capacity to achieve fertilization in vitro.

Immaturity and chromosomal abnormalities in oocytes that fail to develop pronuclei following insemination in vitro.

A total of 293 oocytes that failed to develop pronuclei after insemination in vitro with apparently normal, fertile spermatozoa were obtained from 87 women undergoing therapeutic in-vitro fertilization. The oocytes were investigated cytogenetically to determine the incidence of immaturity and chromosomal abnormalities. Cytogenetic examination was possible in 81% of the preparations, in which immaturity and chromosomal abnormalities were present in 29.5 and 58.7% respectively.

Pregnancy in patients with prosthetic heart valves: the effects of anticoagulation on mother, fetus, and neonate.

Maternal and fetal complications in a consecutive series of 60 pregnancies in 49 patients with prosthetic heart valves were prospectively evaluated. Group 1 consisted of 40 pregnancies in 31 patients who were taking oral anticoagulants. No oral anticoagulation was used in 20 pregnancies in 19 patients (group 2). In group 1 there were three instances of acute valvular thrombosis during the 35 pregnancies in patients with mechanical prostheses, with two maternal deaths. There were two episodes of cerebral embolism, one in group 1 and one in group 2. Patients with isolated aortic valve replacement had fewer maternal complications (2 of 13) than patients with isolated mitral valve replacement (15 of 42) without statistical significance. Severe bioprosthesis dysfunction occurred in 4 of 25 pregnancies (one rupture and three stenosis) with two maternal deaths, one in the puerperium and the other in the postoperative period of cardiac surgery during pregnancy. When analyzing obstetric events we observed seven spontaneous abortions and one hydatidiform mole. All spontaneous abortions occurred in group 1. The incidences of prematurity and low birth weight were significantly higher in group 1 than in group 2 (46.6% vs 10.5%, p less than 0.05, and 50% vs 10.5%, p less than 0.05, respectively). Moreover, there was a significant association between prematurity and the mother's New York Heart Association functional class (61.5% in classes III and IV vs 22.2% in classes I and II, p less than 0.05). There were five neonatal deaths, all in group 1 (p = NS vs group 2). Three infants had warfarin-related congenital defects.(ABSTRACT TRUNCATED AT 250 WORDS)

[Maternal mortality due to heart disease]. / Mortalidade materna por cardiopatia.

A retrospective study on maternal mortality in pregnant women with cardiac disease over a period of eleven years (January 1979 to December 1989) was undertaken. The objective was an analysis of the main aspects of this association. Cardiac disease was diagnosed in 694 patients (4.2%) of a total of 16,423 admitted to the Obstetrics Department of the Escola Paulista de Medicina. As for etiology, rheumatic disease (52.3%); Chagas's disease (19.3%) and congenital disease (8.1%) were the most frequent causes. There were 51 maternal deaths, according to FIGO's definition (1967), corresponding to a maternal mortality rate of 428.2/100,000 livebirths during the same period. Twelve of these maternal deaths were due to cardiac disease (maternal mortality rate of 100.8/100,000 livebirths). The statistical analysis identified the following aspects associated with maternal mortality among patients with cardiac disease: primigravida, lack of adequate prenatal care, and cardiac surgery performed previously to and/or during pregnancy. Congestive heart failure with pulmonary edema (41.7%) and thromboembolism (25.0%) were the most frequent causes of maternal death among patients with cardiac disease. The NYHA functional classification was not a good parameter for pregnancy prognosis: eleven patients (91.7%) were considered as belonging to the favorable group before they became pregnant. Most maternal deaths occurred during the first 72 hours after delivery. Therefore, this period was considered most critical for maternal mortality in patients with cardiac disease. No relation-ship was found among the factors: maternal age, race, marital status, delivery and maternal mortality among patients with cardiac disease.(ABSTRACT TRUNCATED AT 250 WORDS)

[Study of pregnancy with chronic hypertension]. / Contribuição ao estudo da gestação em portadoras de hipertensão arterial crônica.

This is a retrospective study of 189 chronic hypertension patients seen at the Discipline of Obstetrics of the São Paulo Medical School at Hospital São Paulo. The data were fed into a computer and several selected variables and established interrelations were run to have a statistical study by means of non-parametric tests. Hypotheses were rejected at a level of 5.0 percent. Results allow to conclude that there is an association of obesity and chronic hypertensive women to obstetrical occurrences such as delayed intra-uterus growth and pregnancy-specific hypertensive disease. With respect to development during pregnancy, a higher number of newborn mortality was observed and correlated to metabolic disorders, infectious diseases, and problems of the respiratory system. However, the authors did not see a high incidence of congenital malformation. All such results lead to the conclusion that the incidence of fetus death, neonatal mortality, and perinatal mortality are five times more frequent in this group than in the control group.

[Pregnancy in women 40 years of age and over: analysis of variables in the mothers and newborn infants]. / Gestação em mulheres com 40 anos ou mais: análise de variáveis maternas e do recém-nascido.

Although pregnancy in women who are forty years old or more is considered a high risk pregnancy, it has occurred more frequently in recent years. This paper reports an analysis of 205 cases of patients over forty years of age seen at the Obstetrics Department of the São Paulo School of Medicine at the São Paulo Hospital. A control group of 1,153 pregnant women ages ranging from 20 to 29--such age range being considered the proper age for reproduction--was formed for the purpose of comparison. Data were stored in computer and lists of many variables were settled to provide a statistical overview through non-parametric testing based on the nature of the variables. 5% was the level of significance set to reject a null hypothesis. The results permit authors to conclude that pregnant women who are forty years old or over present inadequate biological characteristics for a proper obstetric development, based on the advanced age and on the association of many other adverse factors.

[Maternal mortality in Brazil, 1980]. / Mortalidade materna no Brasil, 1980.

PIP: The authors studied Brazilian maternal mortality by examining official statistics from the country's various geographical regions, including the state of Sao Paulo, Brazil. 1980 was selected because of the possibility of working with data from the Population Census of that year. The principal causes of death in Brazil were hypertension, hemorrhage, puerperal infection, and abortion. In Sao Paulo, where the 4th digit of the IDC is used, the main cause of death was eclampsia. The 2nd was hemorrhage, and the 3rd was infection, whether due to or associated with pregnancy. As for age, the lowest maternal mortality rate occurred in the 20-29 year old age group, the rate was slightly higher for those ages 15-19, and increasing gradually in those ages 30-39 and 40-49. It was not possible to analyze the rates for those ages 10-14 and over age 50 because of lack of data on livebirths. However, there were 18 deaths and 4 deaths respectively in those groups which shows that at opposite poles of the reproductive span, there exists a considerably high mortality rate. In comparing these data with those of other countries, it was found that the majority of deaths are avoidable and that it should be possible to reduce the number considerably by means of better health care for women and by using techniques and resources which are already available. (author's modified)^ieng