Physical activity before and during pregnancy and risk of abnormal glucose tolerance among Hispanic women

AIM

Women diagnosed with abnormal glucose tolerance and gestational diabetes mellitus are at increased risk for subsequent type 2 diabetes, with higher risks in Hispanic women. Studies suggest that physical activity may be associated with a reduced risk of these disorders; however, studies in Hispanic women are sparse.

METHODS

We prospectively evaluated this association among 1241 Hispanic participants in Proyecto Buena Salud. The Pregnancy Physical Activity Questionnaire was used to assess pre, early, and mid pregnancy physical activity. Medical records were abstracted for pregnancy outcomes.

RESULTS

A total of 175 women (14.1%) were diagnosed with abnormal glucose tolerance and 57 women (4.6%) were diagnosed with gestational diabetes. Increasing age and body mass index were strongly and positively associated with risk of gestational diabetes. We did not observe statistically significant associations between total physical activity or meeting exercise guidelines and risk. However, after adjusting for age, BMI, gestational weight gain, and other important risk factors, women in the top quartile of moderate-intensity activity in early pregnancy had a decreased risk of abnormal glucose tolerance (odds ratio=0.48, 95% Confidence Interval 0.27-0.88, Ptrend=0.03) as compared to those in the lowest quartile. Similarly, women with the highest levels of occupational activity in early pregnancy had a decreased risk of abnormal glucose tolerance (odds ratio=0.48, 95% Confidence Interval 0.28-0.85, Ptrend=0.02) as compared to women who were unemployed.

CONCLUSION

In this Hispanic population, total physical activity and meeting exercise guidelines were not associated with risk. However, high levels of moderate-intensity and occupational activity were associated with risk reduction.

Hyperdominance in the Amazonian tree flora

The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.

Tree mortality, recruitment and growth in a bamboo dominated forest fragment in southwestern Amazonia, Brazil

Forest fragmentation affects the structure and dynamics of plant communities, leading to biodiversity loss in forest remnants. In this paper we show that in a bamboo (Guadua weberbaueri Pilger) dominated forest fragment in southwestern Amazonia edge effect may be confounded by bamboo effect, which also occur inside the forest. We measured growth, mortality and, recruitment rate of trees with DBH ≥ 10 cm, in a fragment of bamboo dominated open forest in southwestern Amazonia, state of Acre, Brazil, in 15 plots at the forest edge and 15 plots inside the forest fragment, 500 m away from the border. Time interval between censuses was 1.8 years. The average diameter growth rate differed significantly between edge (3.82 ± 0.10 mm a-1) and interior (2.39 ± 0.18 mm a-1); but there were no differences in annual mortality rate (edge = 3.8 ± 2.5 % a-1 CV = 65.7%; interior = 3.6 ± 2.6% a-1 CV = 72.2%) or in annual recruitment rate (edge = 7.1 ± 3.2% a-1 CV = 45%; interior = 8.9 ± 7.9% a-1 CV = 88.7%). Diameter growth rate, particularly of pioneer and fast-growing trees, is favored by the environmental conditions of the edge, where bamboo abundance is higher. However, the absence of an edge effect on mortality and recruitment could be due to the particular dynamics of bamboo patches, which could be mimicking forest edges and therefore masking possible edge effect in this fragment. We speculate that the mortality and recruitment patterns in fragmented forests of southwestern Amazonia is different from other areas in Amazonia and that bamboo is one of the key controllers of successional processes in these fragments.

Helical post-buckling of a rod in a cylinder: with applications to drill-strings

The helical buckling and post-buckling of an elastic rod within a cylindrical casing arises in many disciplines, but is particularly important in the petroleum industry. Here, a drill-string, subjected to an end twisting moment combined with axial tension or compression, is particularly prone to buckling within its bore-hole—with potentially serious results. In this paper, we make a detailed theoretical study of this type of instability, deriving precise new results for the advanced post-buckling stage when the rod is in continuous contact with the cylinder. Results, including rigorous stability analyses and contact pressure assessments, are presented as equilibrium surfaces to facilitate comparisons with experimental results. Two approximate solutions give insight, universal graphs and parameters, for the practically relevant case of small angles, and highlight the existence of a critical cylinder diameter. Excellent agreement with experiments is achieved.

The nested structure of cancer symptoms. Implications for analyzing co-occurrence and managing symptoms

OBJECTIVE

Although many cancer patients experience multiple concurrent symptoms, most studies have either focused on the analysis of single symptoms, or have used methods such as factor analysis that make a priori assumptions about how the data is structured. This article addresses both limitations by first visually exploring the data to identify patterns in the co-occurrence of multiple symptoms, and then using those insights to select and develop quantitative measures to analyze and validate the results.

METHODS

We used networks to visualize how 665 cancer patients reported 18 symptoms, and then quantitatively analyzed the observed patterns using degree of symptom overlap between patients, degree of symptom clustering using network modularity, clustering of symptoms based on agglomerative hierarchical clustering, and degree of nestedness of the symptoms based on the most frequently co-occurring symptoms for different sizes of symptom sets. These results were validated by assessing the statistical significance of the quantitative measures through comparison with random networks of the same size and distribution.

RESULTS

The cancer symptoms tended to co-occur in a nested structure, where there was a small set of symptoms that co-occurred in many patients, and progressively larger sets of symptoms that co-occurred among a few patients.

CONCLUSIONS

These results suggest that cancer symptoms co-occur in a nested pattern as opposed to distinct clusters, thereby demonstrating the value of exploratory network analyses to reveal complex relationships between patients and symptoms. The research also extends methods for exploring symptom co-occurrence, including methods for quantifying the degree of symptom overlap and for examining nested co-occurrence in co-occurrence data. Finally, the analysis also suggested implications for the design of systems that assist in symptom assessment and management. The main limitation of the study was that only one dataset was considered, and future studies should attempt to replicate the results in new data.

Drought-mortality relationships for tropical forests

*The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. *We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. *In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. *These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality.

Drought sensitivity of the Amazon rainforest

Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.

Estimation of biomass and carbon stocks: the case of the Atlantic Forest

The main objective of this paper is to present and discuss the best methods to estimate live above ground biomass in the Atlantic Forest. The methods presented and conclusions are the products of a workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest". Aboveground biomass (AGB) in tropical forests is mainly contained in trees. Tree biomass is a function of wood volume, obtained from the diameter and height, architecture and wood density (dry weight per unit volume of fresh wood). It can be quantified by the direct (destructive) or indirect method where the biomass quantification is estimated using mathematical models. The allometric model can be site specific when elaborated to a particular ecosystem or general that can be used in different sites. For the Atlantic Forest, despite the importance of it, there are only two direct measurements of tree biomass, resulting in allometric models specific for this ecosystem. To select one or other of the available models in the literature to estimate AGB it is necessary take into account what is the main question to be answered and the ease with which it is possible to measure the independent variables in the model. Models that present more accurate estimates should be preferred. However, more simple models (those with one independent variable, usually DBH) can be used when the focus is monitoring the variation in carbon storage through the time. Our observations in the Atlantic Forest suggest that pan-tropical relations proposed by Chave et al. (2005) can be confidently used to estimated tree biomass across biomes as long as tree diameter (DBH), height, and wood density are accounted for in the model. In Atlantic Forest, we recommend the quantification of biomass of lianas, bamboo, palms, tree ferns and epiphytes, which are an important component in this ecosystem. This paper is an outcome of the workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest", that was conducted at Ubatuba, São Paulo, Brazil, between 4 and 8 December 2006 as part of the Brazilian project "Ombrophylus Dense Forest floristic composition, structure and function at the Núcleos Picinguaba and Santa Virginia of the Serra do Mar State Park", BIOTA Gradiente.

Serotonin in the nervous system of the head region of the land planarian Bipalium kewense

The presence and distribution of serotonin (5-hydroxytryptamine, or 5-HT) in the head region of the land planarian Bipalium kewense has been investigated by an indirect immunofluorescence technique combined with confocal scanning laser microscopy (CSLM), and also by immunogold labeling at ultrastructural level. Serotonin immunoreactivity (IR) was restricted to elements of the nervous system, such as the cerebral ganglion, and the peripheral nerve net. Most of 5-HT-immunoreactive neurons are at the periphery of the brain; they were identified as unipolar, bipolar, and multipolar neurons. The ultrastructural results using immunogold labeling confirm the location of 5-HT within electron-dense vesicles (50-120 nm in diameter), clustered both in the cell bodies and in their processes. The intense 5-HT-IR herein demonstrated for B. kewense adds new data to the poorly studied nervous system of land planarians.

Seasonal differences in lamb birthweight do not arise from inherent differences in the oocyte and/or early embryo

The aim of this study was to determine whether previously observed seasonal differences in conceptus development in ewes are attributable to inherent differences in the oocyte and/or early embryo. Day 6 embryos were recovered from 50 ewes subjected to a standard oestrus synchronization, superovulation and laparoscopic artificial insemination protocol during October (peak breeding season) and April (transition to anoestrus). During the following October, 40 grade 1 and 2 embryos from each month, which had been cryopreserved at the late morula or unexpanded blastocyst stage, were thawed and transferred in singleton to synchronous recipients. Resulting pregnancies were monitored to term. For ewes receiving October- and April-produced embryos, overall mean +/- SEM liveweight at the time of embryo transfer was 72 +/- 0.7 kg, body condition score was 3.1 +/- 0.04 units, and the number of corpora lutea on the ovaries was 2.7 +/- 0.11 per ewe. Thirty-one and 27 ewes, respectively, became pregnant and their gestation lengths were 147 +/- 0.2 and 147 +/- 0.3 days. There was no effect of month of embryo production on peripheral ovine pregnancy-associated glycoprotein concentrations during pregnancy or on fetal and placental characteristics at term, but, for each month, male lambs were heavier than females and were associated with larger placentae. Lamb birthweight was positively correlated with placental weight (r2 = 0.474, P<0.001) and the total weight of cotyledonary tissue (r2 = 0.429, P<0.001), but not to the number of cotyledons. Results demonstrate close relationships between fetal and placental weights at term, and that seasonal effects on conceptus development in ewes do not arise from inherent differences in the oocyte and/or early embryo.

Interaction between Saccharomyces cerevisiae and chrysotile

The interaction between Saccharomyces cerevisiae and chrysotile fibers was studied by scanning electron microscopy. The yeast cells adhere preferentially to the fibrils. In the extreme case, all the adhered fibrils were broken, resulting in a complete coverage of the surface. The chrysotile covered cells showed less buds, but retained metabolic capacities, and were fully active in fermentation experiments after one year. The interaction degree was depending on contact time and adhesion medium. The longer the contact period, the stronger the interaction between the cells and the fibers. Cells adhered in water show poor entrapment after short contact time, but were highly entrapped after longer periods and did not show any agglomerates. Cells adhered in the presence of nutrients showed a lower entrapment and a higher degree of cellular growth.

Modulation of human papillomavirus type 16 mRNA in cervical invasive carcinoma patients by interferon-alpha therapy

Mechanisms by which interferon produces papilloma regression remain largely unknown. We analyzed biopsies from three cervical invasive carcinoma patients treated with interferon-alpha (IFN-alpha) administered both topically and i.m. for 15 days. All specimens contained human papillomavirus (HPV-16) DNA as determined by polymerase chain reaction using specific HPV-16 E7 primers. Interestingly, in two patients. HPV-16 mRNA expression was reduced (44% and 67%, respectively) after IFN treatment. Upregulation of 2-5 A synthetase and PKR mRNA levels were indicative of the IFN effect. A larger study should be initiated to see whether IFN-alpha modulates the HPV-16 mRNA levels in tumor biopsies from cervical carcinoma patients.

Catecholamines and experimental stress ulcer: morphological and biochemical changes in the gastric mucosa

A model for the production of gastric mucosal haemorrhages and ulcers, similar in morphology and distribution to those seen in stress states in man, has been produced by the intraperitoneal injection of adrenaline in single, double or treble doses of 0.6 mg/kg. Lesions were produced in 2 or 3 h, without ligation of the pylorus. Severe mucosal changes were associated with a fall in gastric mucosal histamine concentration. Mucosal serotonin did not change. Rises in mucosal adrenaline were accompanied by a fall noradrenaline, total catecholamine levels being unchanged.

Fine structural observations on the protonephridium of the terrestrial triclad Geoplana pasipha

The protonephridial system of the terrestrial triclad Geoplana pasipha was studied by electron microscopy. In general construction it conforms to that of the freshwater planarian Dugesia tigrina (McKanna, 1968, 1968a). Ultrastructural details permit the identification of proximal, collecting, osmoregulatory and nephridiopore regions. Intralumenal material is frequently observed within the tubules, whose cells are always joined by septate junctions. Cilia are numerous and possibly contribute to the flow of water and solutes along the system. Proximal tubules have a peculiar, particulate membrane coat, while a continuous coat, densely stainable with ruthenium red lines the more distal, unciliated tubules.