Contribución de los heterótrofos a la calcificación secundaria en arrecifes marginales del Pacífico mexicano

Background. Sclerobionts (e.g., calcareous algae, bryozoans, polychaetes, mollusks, and barnacles) produce reef calcium carbonate (CaCO3). Their contribution is key to maintaining positive CaCO3 balances, especially in marginal reefs. Objective. To compare the production of CaCO3 by sclerobionts in two marginal reefs of the Mexican Pacific: Las Gatas (LG), in Zihuatanejo Guerrero Bay, and La Llave (LL), in Bahía de Los Angeles (Gulf of California). Methods. CAUs (Calcification/Accretion Units) were used to promote sclerobiont recruitment during two deployment times: 6 and 15 months. Results. The calcification rate was high at six months and then decreased due to rapid colonization and initial growth, followed by a decrease over time. Sclerobionts deposited 1.2 ± 0.4 kg CaCO3 m-2 yr-1 in LG, which represents 7% of the production of branching corals in the Mexican South Pacific (17.2 kg m-2 yr-1), while in LL, they deposited 2.1 ± 0.7 kg CaCO3 m-2 yr-1; equivalent to 20% of the production of massive corals in the area (10.1 kg m-2 yr-1). The groups that deposited most CaCO3were mollusks and bryozoans in LG (up to 0.65 ± 0.16 kg m-2 yr-1) and barnacles in LL (up to 2.32 ± 0.35 kg m-2 yr-1). Conclusions. These results highlight the role of heterotrophs as secondary calcifiers both in LG, a site impacted by anthropogenic activity, and in LL, an area with low anthropogenic impact but high biological productivity associated with upwellings. This finding implies that the environmental conditions at the study sites limit the calcification of primary calcifiers (i.e., corals and CCA) but promote that of secondary calcifiers, with potential geomorphic repercussionsAntecedentes. Los esclerobiontes (e.g., algas calcáreas, briozoos, poliquetos, moluscos, y balanos) par-ticipan en la producción de carbonato de calcio (CaCO3) arrecifal. Su contribución es vital para mantener balances de CaCO3 positivos, especialmente en arrecifes marginales. Objetivo. Comparar la producción de CaCO3 por esclerobiontes en un arrecife sujeto a estrés antropogénico - Las Gatas (LG), en la bahía de Zihua-tanejo Guerrero, y otro bajo condiciones ambientales altamente fluctuantes - La Llave (LL), en Bahía de Los Ángeles (Golfo de California). Métodos. Se utilizaron CAUs (Calcification/Accretion Units) para promover el reclutamiento de esclerobiontes durante dos periodos de inmersión: 6 y 15 meses. Resultados. La tasa de calcificación fue alta a los 6 meses y luego disminuyó debido a la rápida colonización y crecimiento inicial seguido de una disminución con el tiempo. Los esclerobiontes depositaron 1.2 ± 0.4 kg CaCO3 m-2 año-1 en LG, lo que representa el 7% de la producción de corales ramificados en el Pacífico sur mexicano (17.2 kg m-2año-1), mientras que en LL depositaron 2.1 ± 0.7 kg CaCO3 m-2 año-1, equivalente al 20% de la producción de corales masivos en la zona (10.1 kg m-2 año-1). Los grupos que más CaCO3 depositaronfueron los moluscos y los briozoos en LG (hasta 0.65 ± 0.16 kg m-2 año-1), y los balanos en LL (hasta 2.32 ± 0.35 kg m-2 año-1). Conclusiones. Estos resultados destacan el papel de los heterótrofos como calcificadores secundarios tanto en LG, un sitio impactado por actividad antropogénica, como en LL, un sitio con bajo impacto antropogénico, pero con alta productividad biológica asociada a surgencias. Este hallazgo implica que las condiciones am-bientales en los sitios de estudio limitan la calcificación de los calcificadores primarios (i.e., corales y CCA) pero estimulan la de calcificadores secundarios, con potenciales repercusiones geomórficas

Prevalence of orthostatic hypotension in a series of elderly Mexican institutionalized patients

Background: Orthostatic hypotension (OH) is a common problem among the elderly. It is associated with an increase in morbidity and mortality, but its prevalence in Mexico is unknown. Methods: We conducted a cross-sectional prospective study of intern patients at several Mexican elderly assistance institutions. We carried out a history and took blood pressure readings in a seated position, immediately after standing up, and again after 3 min of standing up. Results: We evaluated 132 patients, mean age 82.3 ± 9.5 years, 74.1% of them female. Thirty-nine (29.3%) subjects had OH. They had a higher prevalence of hypothyroidism, Parkinson’s disease, depression and alcoholism. Their Minimental result was 15.45 ± 7.2 vs 16.12 ± 7.9 (p = 0.6) among those without OH, and their quality of life (Minnesota scale) was 12.1 ± 7.3 vs 9.15 ± 7.05 (p = 0.03). They used more ACEI, digoxin and levothyroxin. Hypertension and alcoholism showed respectively a RR of 2.6 (95% CI 0.9–7.6, p = 0.06) and 3.18 (95% CI 0.96–10.48, p = 0.05) to develop OH. Conclusions: OH was present in 29.3% of the studied population. A third of them had hypertension. The use of different medications does not solely explain OH, so it is necessary to look for different associations. Among those, chronic alcoholism stands out. OH is associated with a poorer quality of life and cognitive performance. OH is asymptomatic in most cases. (Cardiol J 2011; 18, 3: 282–288

VID22 counteracts G-quadruplex-induced genome instability

Genome instability is a condition characterized by the accumulation of genetic alterations and is a hallmark of cancer cells. To uncover new genes and cellular pathways affecting endogenous DNA damage and genome integrity, we exploited a Synthetic Genetic Array (SGA)-based screen in yeast. Among the positive genes, we identified VID22, reported to be involved in DNA double-strand break repair. vid22Δ cells exhibit increased levels of endogenous DNA damage, chronic DNA damage response activation and accumulate DNA aberrations in sequences displaying high probabilities of forming G-quadruplexes (G4-DNA). If not resolved, these DNA secondary structures can block the progression of both DNA and RNA polymerases and correlate with chromosome fragile sites. Vid22 binds to and protects DNA at G4-containing regions both in vitro and in vivo. Loss of VID22 causes an increase in gross chromosomal rearrangement (GCR) events dependent on G-quadruplex forming sequences. Moreover, the absence of Vid22 causes defects in the correct maintenance of G4-DNA rich elements, such as telomeres and mtDNA, and hypersensitivity to the G4-stabilizing ligand TMPyP4. We thus propose that Vid22 is directly involved in genome integrity maintenance as a novel regulator of G4 metabolism

Tuberculosis Outbreak Investigations in the United States, 2002–2008

To understand circumstances of tuberculosis transmission that strain public health resources, we systematically reviewed Centers for Disease Control and Prevention (CDC) staff reports of US outbreaks in which CDC participated during 2002–2008 that involved >3 culture-confirmed tuberculosis cases linked by genotype and epidemiology. Twenty-seven outbreaks, representing 398 patients, were reviewed. Twenty-four of the 27 outbreaks involved primarily US-born patients; substance abuse was another predominant feature of outbreaks. Prolonged infectiousness because of provider- and patient-related factors was common. In 17 outbreaks, a drug house was a notable contributing factor. The most frequently documented intervention to control the outbreak was prioritizing contacts according to risk for infection and disease progression to ensure that the highest risk contacts were completely evaluated. US-born persons with reported substance abuse most strongly characterized the tuberculosis outbreaks in this review. Substance abuse remains one of the greatest challenges to controlling tuberculosis transmission in the United States

Childhood acute leukemias are frequent in Mexico City: descriptive epidemiology

<p>Abstract</p> <p>Background</p> <p>Worldwide, acute leukemia is the most common type of childhood cancer. It is particularly common in the Hispanic populations residing in the United States, Costa Rica, and Mexico City. The objective of this study was to determine the incidence of acute leukemia in children who were diagnosed and treated in public hospitals in Mexico City.</p> <p>Methods</p> <p>Included in this study were those children, under 15 years of age and residents of Mexico City, who were diagnosed in 2006 and 2007 with leukemia, as determined by using the International Classification of Childhood Cancer. The average annual incidence rates (AAIR), and the standardized average annual incidence rates (SAAIR) per million children were calculated. We calculated crude, age- and sex-specific incidence rates and adjusted for age by the direct method with the world population as standard. We determined if there were a correlation between the incidence of acute leukemias in the various boroughs of Mexico City and either the number of agricultural hectares, the average number of persons per household, or the municipal human development index for Mexico (used as a reference of socio-economic level).</p> <p>Results</p> <p>Although a total of 610 new cases of leukemia were registered during 2006-2007, only 228 fit the criteria for inclusion in this study. The overall SAAIR was 57.6 per million children (95% CI, 46.9-68.3); acute lymphoblastic leukemia (ALL) was the most frequent type of leukemia, constituting 85.1% of the cases (SAAIR: 49.5 per million), followed by acute myeloblastic leukemia at 12.3% (SAAIR: 6.9 per million), and chronic myeloid leukemia at 1.7% (SAAIR: 0.9 per million). The 1-4 years age group had the highest SAAIR for ALL (77.7 per million). For cases of ALL, 73.2% had precursor B-cell immunophenotype (SAAIR: 35.8 per million) and 12.4% had T-cell immunophenotype (SAAIR 6.3 per million). The peak ages for ALL were 2-6 years and 8-10 years. More than half the children (58.8%) were classified as high risk. There was a positive correlation between the average number of persons per household and the incidence of the pre-B immunophenotype (Pearson's r, 0.789; P = 0.02).</p> <p>Conclusions</p> <p>The frequency of ALL in Mexico City is among the highest in the world, similar to those found for Hispanics in the United States and in Costa Rica.</p