The relative biological effectiveness of 670 MeV/A neon as a function of depth in water for a tissue model

Linear energy transfer (LET infinity) spectra of identified charge fragments and primaries, produced by nuclear interactions of 670 MeV/A neon in water, were measured along the unmodulated Bragg curve of the neon beam. The relative biological effectiveness (RBE) values for spermatogonial cell killing, as reported on the basis of weight loss assay of mouse testes irradiated with beams of approximately constant single LET infinity, were summed over the particle LET infinity spectra to obtain an effective RBE for each charged-particle species, as a function of water absorber thickness. The resultant values of effective RBE were combined to obtain an effective RBE for the mixed radiation field. The RBE calculated in this way was compared with experimental RBEs obtained for spermatogonial cell killing in the mixed radiation field produced by neon ions traversing a thick water absorber. Discrepancies of 10-40% were observed between the calculated RBE and the RBE measured in the mixed radiation field. Part of this discrepancy can be attributed to undetected low-Z fragments, whose contribution is not included in the calculation, leading to an overestimated value for the calculated RBE. On the other hand, calculated values 10% greater than the measured RBE are explained as track structure effects due to the higher radial ionization density near neon tracks relative to the ionization density near the silicon tracks used to fit the RBE vs LET infinity data.     

Effects of N-fertilizers,straw, and dry fallow on the nitrogen balance of a flooded soil planted with rice

Summary Nitrogen balance studies were made on rice (Oryza sativa) grown in flooded soil in pots. A low rate of fertilizer (5.64 mg N. kg⁻¹ soil) did not depress the N gain, but a high rate (99.72 mg N. kg⁻¹ soil) elminated the N gain. Soil N loss was negligible since¹⁵N applied as ammonium sulfate and thoroughly mixed with the soil was recovered from the soil-plant system after 3 crops. The observed N gain, therefore, was caused by N₂-fixation, not by a reduction of soil N loss. Straw enhanced N gain at the rate of 2–4 mg per g straw. However, this gain was not observed when soil N availability was high. Dry fallow between rice crops decreased the N gain.     

Ethanol-responsive gene expression in neural cell cultures.

We have studied the molecular mechanisms underlying neuronal adaptation to chronic ethanol exposure. NG108-15 neuroblastoma cells were used to perform a detailed analysis of ethanol-induced changes in neuronal gene expression. High resolution, quantitative two-dimensional (2-D) gel electrophoresis of in vitro translation products showed both dose-dependent increases and decreases in specific mRNA abundance following treatment with ethanol at concentrations seen in actively drinking alcoholics (50-200 mM). Dose response curves for representative members of the increasing or decreasing response groups had very similar profiles, suggesting that similar mechanisms may regulate members of a response group. Some mRNAs that increased with ethanol treatment appeared identical to species induced by heat shock while other mRNAs were only induced by ethanol. We conclude that chronic ethanol exposure can produce specific coordinate changes in expression of neuronal mRNAs, including some members of the stress protein response. However, the overall pattern of ethanol-responsive gene expression is distinct from the classical heat shock subgroup of stress proteins response. Changes in gene expression and specifically, mechanisms regulating a subset of stress protein expression, could be an important aspect of neuronal adaptation to chronic ethanol seen in alcoholics.     

Pseudomonas aeruginosa acid phosphatase and cholinesterase induced by choline and its metabolic derivatives may contain a similar anionic peripheral site

Summary Different compounds derived from choline, and obtained by demethylation or by oxidation of the primary alcohol group with subsequent N-demethylation, were tested as inducer agents of acid phosphatase and cholinesterase in Ps. aeruginosa. It was found that betaine and dimethylglycine were the most effective inducers of both enzyme activities. These metabolites including choline itself, were not inducers of acid phosphatase and cholinesterase in other Gram-negative bacteria such as: Escherichia coli, Salmonella typhimurium, Shigella flexneri, Enterobacter liquefacciens and Proteus mirabilis. The acid phosphatase activities found in these bacteria were not inhibited in vitro by choline, betaine and phosphorylcholine. From these results it may be concluded that the acid phosphatase activity from Ps. aeruginosa is different from the same activity observed in the other bacteria. In addition, it is also shown that Ps. aeruginosa acid phosphatase and cholinesterase were inhibited by a number of compounds containing a positively charged amino group, with methyl or ethyl groups bound to it. These results seem to confirm that Ps. aeruginosa acid phosphatase and cholinesterase may contain a similar anionic site.     

Nitrogen fixation throughout growth,and varietal differences in nitrogen fixation by the rhizosphere of rice planted in pots

Summary The nitrogen-fixing activity in the rhizospheres of various rices was measured by the acetylene-reduction method throughout plant growth in green-house pots. The activity began to increase 4 weeks after transplanting, increased until heading stage, then decreased. The concentrations of exchangeable ammonium and sugars in the soil were not related to the variation of nitrogen-fixing activity during rice growth.The nitrogen-fixing activities in the rhizospheres of 41 rice varieties in pots were measured to discover varietal differences. Levels of nitrogen fixation were highly correlated with the rices' dry root weight at heading stage.     

Developmental changes in the breakdown of brain tubulin by cerebral cathepsin D

The activity of cathepsin D on hemoglobin and on cytoplasmic tubulin was measured in brain preparations at different ages—in newborn, 10-and 21-day-old, and young adult rats. Enzyme activity increased after birth, reaching a maximum at around 21 days, and then declined. This increase was not parallel with decreased turnover of proteins during development, but was parallel with decreasing level and increasing microheterogeneity and rate of assembly of tubulin during development. The breakdown of tubulin was heterogeneous, with initial fast breakdown of a large portion, followed by breakdown at a lower rate. This heterogeneity in breakdown persisted throughout development. The breakdown of tubulin, unlike that of hemoglobin, was at all ages greater at pH 5.8 than at pH 3.2. The possible role of cathepsin D in tubulin metabolism and the developmental changes under physiological conditions need further exploration.     

Pure red cell hypoplasia associated with long-arm deletion of chromosome 5

Summary A further instance of the new hematologic entity of pure red cell hypoplasia with deletion of the long arm of a chromosome 5(5q-) was seen in a 59-year-old white male. Examination of the bone marrow showed depressed erythroid cells with normal granulocytic and megakaryocytic precursors. Chromosomal analysis showed deletion of a chromosome 5 without any apparent translocation. This karyotype may be associated with acute leukemia.     

Epidemiological Characterization of Influenza A(H1N1)pdm09 Cases from 2009 to 2010 in Baguio City,the Philippines

Background

Baguio City, Philippines experienced its first influenza A(H1N1)pdm09 [A(H1)pdm09] case in May 2009. In spite of numerous reports describing the epidemiological and clinical features of A(H1)pdm09 cases, there are no studies about A(H1)pdm09 epidemiology in the Philippines, where year-round influenza activity was observed.

Objectives

We aimed to investigate the epidemiological and clinical features of A(H1)pdm09 in pandemic and post-pandemic periods.

Methods

Data were collected under enhanced surveillance of influenza-like illness (ILI) and severe acute respiratory infection (SARI) from January 2009 to December 2010. RT-PCR was used to detect A(H1)pdm09, following the protocol of the United States Centers for Disease Control and Prevention. The reproduction number was computed as a simple exponential growth rate. Differences in proportional and categorical data were examined using chi-square test or Fishers’ exact test.

Results and Conclusions

The outbreak was observed from week 25 to 35 in 2009 and from week 24 to 37 in 2010. The highest proportion of cases was among children aged 5–14 years. The number of ILI outpatients was 2.3-fold higher in 2009 than in 2010, while the number of inpatients was 1.8-fold higher in 2009. No significant difference in gender was observed during the two periods. The clinical condition of all patients was generally mild and self-limiting, with only 2 mortalities among inpatients in 2009. The basic reproduction number was estimated as 1.16 in 2009 and 1.05 in 2010 in the assumption of mean generation time as 2.6 days. School children played a significant role in facilitating influenza transmission.     

Engineering production of antihypertensive peptides in plants

To date, a number of antihypertensive peptides (AHPs) have been identified. Most of these are derived from proteins present in common edible consumables, including milk, egg, and plant foods. Consumption of these foods serves as means of AHP delivery and thus contributing favorable health benefits. It is hypothesized that food crops, either over-expressing AHP precursor proteins or producing particular peptides as heterologous components, may serve as viable vehicles for production and delivery of functional foods as alternative hypertension therapies. In recent years, genetic engineering efforts have been undertaken to add value to functional foods. Pioneering approaches have been pursued in several crop plants, such as rice and soybean. In this review, a summary of current tools used for discovery of new AHPs, as well as strategies and perspectives of capitalizing on these AHPs in genetic engineering efforts will be presented and discussed. The implications of these efforts on the development of functional foods for preventing and treating hypertension are also presented.     

50 years of the Revista de Biologia Tropical: its contribution to the development of the Geo-Paleontology

The geosciences contribution along the 50 years of the Revista de Biología Tropical had been scarcity and episodic. Until now there are 2374 papers but only 21 (0.88%) have some relation with geological sciences. It's possible to recognize two periods with geological contributions, one between 1963 and 1978. It's appropriate to underline the importance of the biologist L. D. Gómez with his contributions about Costa Rican Paleobotanic in this period. The other period includes from 1988 to the present, and it's typified by an increase of biologist and geologist participation in different topics regarding with geosciences. Foreign and national researches are in the same ratio and belong from several countries like Costa Rica, México and Dominican Republic. The subjects are concerning mainly about fossil taxonomy (Paleontology: 81%), only 19% are related with geological topics. Such distribution could be explained because the affinity between the fossil studies and the biological sciences.