Comparative incidence of cancer in HIV-AIDS patients and transplant recipients

BackgroundStudies have found a relationship between decreased immunity and increased incidence of cancer.MethodsA systematic review of observational studies evaluating the incidence of cancer in both organ recipients and people with HIV/AIDS compared with the general population. Eligible studies were searched up to March 2011 in the following databases: Pubmed, Embase, Scielo, Cancerlit and Google scholar. In this study, the standardized incidence ratios (SIR) of cancer in people with HIV/AIDS and of organ transplant recipients were compared with those found among the general population.ResultsTwenty-five studies of transplant and HIV-associated cancer risk, involving 866 776 people with HIV/AIDS or organ recipients and 21 260 new cases of cancer, were included. The risk for the development of new cancer cases was higher among people with HIV/AIDS (SIR = 4, IC95% 3.78–4.24) and who received organs (SIR = 3.28, IC95% 3.06–3.52) when compared with the general population.ConclusionSimilar SIR in both immunocompromised populations suggests that the weakened immune system is responsible for the increased risk of new cases of cancer among these groups. Research investments are needed to develop effective cancer prevention strategies in these populations.     

Implementation of dual-source RF excitation in 3 T MR-scanners allows for nearly identical ADC values compared to 1.5 T MR scanners in the abdomen

Background

To retrospectively and prospectively compare abdominal apparent diffusion coefficient (ADC) values obtained within in a 1.5 T system and 3 T systems with and without dual-source parallel RF excitation techniques.

Methodology/Principal Findings

After IRB approval, diffusion-weighted (DW) images of the abdomen were obtained on three different MR systems (1.5 T, a first generation 3 T, and a second generation 3 T which incorporates dual-source parallel RF excitation) on 150 patients retrospectively and 19 volunteers (57 examinations total) prospectively. Seven regions of interest (ROI) were throughout the abdomen were selected to measure the ADC. Statistical analysis included independent two-sided t-tests, Mann-Whitney U tests and correlation analysis. In the DW images of the abdomen, mean ADC values were nearly identical with nonsignificant differences when comparing the 1.5 T and second generation 3 T systems in all seven anatomical regions in the patient population and six of the seven in the volunteer population (p>0.05 in all distributions). The strength of correlation measured in the volunteer population between the two scanners in the kidneys ranged from r = 0.64–0.88 and in the remaining regions (besides the spleen), r>0.85. In the patient population the first generation 3 T scanner had different mean ADC values with significant differences (p<0.05) compared to the other two scanners in each of the seven distributions. In the volunteer population, the kidneys shared similar ADC mean values in comparison to the other two scanners with nonsignificant differences.

Conclusions/Significance

A second generation 3 T scanner with dual-source parallel RF excitation provides nearly identical ADC values compared with the 1.5 T imaging system in abdominal imaging.     

Low Bone Strength Is a Manifestation of Phenylketonuria in Mice and Is Attenuated by a Glycomacropeptide Diet

Purpose

Phenylketonuria (PKU), caused by phenylalanine (phe) hydroxylase loss of function mutations, requires a low-phe diet plus amino acid (AA) formula to prevent cognitive impairment. Glycomacropeptide (GMP), a low-phe whey protein, provides a palatable alternative to AA formula. Skeletal fragility is a poorly understood chronic complication of PKU. We sought to characterize the impact of the PKU genotype and dietary protein source on bone biomechanics.

Procedures

Wild type (WT; Pah^+/+) and PKU (Pah^enu2/enu2) mice on a C57BL/6J background were fed high-phe casein, low-phe AA, and low-phe GMP diets between 3 to 23 weeks of age. Following euthanasia, femur biomechanics were assessed by 3-point bending and femoral diaphyseal structure was determined. Femoral ex vivo bone mineral density (BMD) was assessed by dual-enengy x-ray absorptiometry. Whole bone parameters were used in prinicipal component analysis. Data were analyzed by 3-way ANCOVA with genotype, sex, and diet as the main factors.

Findings

Regardless of diet and sex, PKU femora were more brittle, as manifested by lower post-yield displacement, weaker, as manifested by lower energy and yield and maximal loads, and showed reduced BMD compared with WT femora. Four principal components accounted for 87% of the variance and all differed significantly by genotype. Regardless of genotype and sex, the AA diet reduced femoral cross-sectional area and consequent maximal load compared with the GMP diet.

Conclusions

Skeletal fragility, as reflected in brittle and weak femora, is an inherent feature of PKU. This PKU bone phenotype is attenuated by a GMP diet compared with an AA diet.     

Surface Plasmon Polariton Emission Prompted by Organic Nanofibers on Thin Gold Films

The excitation of surface plasmon polaritons (SPP) at a gold?Cvacuum interface by femtosecond light pulses mediated by organic nanofiber-induced dielectric perturbations is observed using interferometric time-resolved photoemission electron microscopy. The experimental data are quantitatively reproduced by analytic simulations, where the nanofibers are considered as superior source of the SPP emission. The flexibility and tuneability of phenylene-based nanofibers in their morphology and intrinsic optical properties open up future applications to fabricate custom-designed nanoscale sources of SPP.     

Unchanged beta-adrenergic stimulation of cardiac L-type calcium channels in Ca v 1.2 phosphorylation site S1928A mutant mice

Phosphorylation of serine 1928 (Ser(1928)) of the cardiac Ca(v)1.2 subunit of L-type Ca(2+) channels has been proposed as the mechanism for regulation of L-type Ca(2+) channels by protein kinase A (PKA). To test this directly in vivo, we generated a knock-in mouse with targeted mutation of Ser(1928) to alanine. This mutation did not affect basal L-type current characteristics or regulation of the L-type current by PKA and the beta-adrenergic receptor, whereas the mutation abolished phosphorylation of Ca(v)1.2 by PKA. Therefore, our data show that PKA phosphorylation of Ser(1928) of Ca(v)1.2 is not functionally involved in beta-adrenergic stimulation of Ca(v)1.2-mediated Ca(2+) influx into the cardiomyocyte.     

Short-term dynamics of bacterial communities in a tidally affected coastal ecosystem

Tidal effects on the composition of free-living (FL) and particle-associated (PA) bacterial communities were studied in a tidal flat ecosystem in the southern North Sea. Denaturing gradient gel electrophoresis targeting the 16S rRNA gene and the 16S rRNA of Bacteria, Bacteroidetes, Alphaproteobacteria and the Roseobacter clade was applied. Despite strong tidal variations in the quantity and, depending on the season, also the quality of suspended matter as well as variations in bacterial activity, the bacterial community composition remained rather stable. FISH showed some variations of the community composition, but these were not related to typical tidal situations. Variations were higher during tidal cycles in May and July compared with November. Bacteroidetes, Alpha- and Gammaproteobacteria constituted the majority of the bacterial communities but relative proportions of the different groups varied considerably. On particles, Betaproteobacteria were also detected to substantial proportions. The Roseobacter clade constituted up to 90% of FL but only 30% of PA Alphaproteobacteria. Banding patterns of the Bacteroidetes-specific amplicons, and in particular those targeting the 16S rRNA, revealed tidally induced effects, as several bands appeared or disappeared at distinct events such as slack water or resuspension. Sequencing of prominent bands revealed predominantly phylotypes reported previously from this ecosystem.     

Characterization of gamma-tocopherol methyltransferases from Capsicum annuum L and Arabidopsis thaliana.

Tocopherols are essential micronutrients in human and animal nutrition due to their function as lipophilic antioxidants. They are exclusively synthesized by photosynthetic organisms including higher plants. Despite the attributed beneficial health effects and many industrial applications, research on the tocopherol biosynthetic pathway and its regulation in plants is still limited. In the work presented here we performed a detailed biochemical characterization of a gamma-tocopherol methyltransferase (gamma-TMT) from Arabidopsis thaliana and of a gamma-TMT purified from Capsicum annuum fruits, a tissue with high accumulation of tocopherols. The biochemical characteristics of both enzyme preparations were remarkably similar including substrate specificities. Both enzymes converted delta- and gamma- into beta- and alpha-tocopherol, respectively, but beta-tocopherol was not accepted as a substrate, pointing to a specific methylation at the C(5)-position of the tocopherol aromatic head group. A kinetic analysis performed with the Arabidopsis enzyme was consistent with an iso-ordered bi-bi type reaction mechanism. Our results emphasize the role of gamma-TMT in regulating the spectrum of accumulated tocopherols in plants.     

Microbial Community Structure in Midgut and Hindgut of the Humus-Feeding Larva of Pachnoda ephippiata (Coleoptera: Scarabaeidae)

The guts of soil-feeding macroinvertebrates contain a complex microbial community that is involved in the transformation of ingested soil organic matter. In a companion paper (T. Lemke, U. Stingl, M. Egert, M. W. Friedrich, and A. Brune, Appl. Environ. Microbiol. 69:6650-6658, 2003), we show that the gut of our model organism, the humivorous larva of the cetoniid beetle Pachnoda ephippiata, is characterized by strong midgut alkalinity, high concentrations of microbial fermentation products, and the presence of a diverse, yet unstudied microbial community. Here, we report on the community structure of bacteria and archaea in the midgut, hindgut, and food soil of P. ephippiata larvae, determined with cultivation-independent techniques. Clone libraries and terminal restriction fragment length polymorphism analysis of 16S rRNA genes revealed that the intestines of P. ephippiata larvae contain a complex gut microbiota that differs markedly between midgut and hindgut and that is clearly distinct from the microbiota in the food soil. The bacterial community is dominated by phylogenetic groups with a fermentative metabolism (Lactobacillales, Clostridiales, Bacillales, and Cytophaga-Flavobacterium-Bacteroides [CFB] phylum), which is corroborated by high lactate and acetate concentrations in the midgut and hindgut and by the large numbers of lactogenic and acetogenic bacteria in both gut compartments reported in the companion paper. Based on 16S rRNA gene frequencies, Actinobacteria dominate the alkaline midgut, while the hindgut is dominated by members of the CFB phylum. The archaeal community, however, is less diverse. 16S rRNA genes affiliated with mesophilic Crenarchaeota, probably stemming from the ingested soil, were most frequent in the midgut, whereas Methanobacteriaceae-related 16S rRNA genes were most frequent in the hindgut. These findings agree with the reported restriction of methanogenesis to the hindgut of Pachnoda larvae.     

The nutritional value of organic detrital aggregate in the diet of fathead minnows

1. The nutritional value of detrital aggregate, which refers to the mixture of plant debris (i.e. organic detritus) and microorganisms, in the diets of fathead minnows ( Pimephales promelas Rafinesque) was assessed in experiments using surface benthic samples from three sites in Clear Lake (Houghton County, Michigan, U.S.A.).
2. In the first experiment, fish were fed small (<250 μm) and large (250–1000 μm) particle detritus from one profundal and two littoral sites. Fish in all treatments lost weight. However, fish fed detritus from the littoral erosional site, where wild fish forage intensively, had significantly lower weight loss.
3. In the second experiment, fish were fed various quantities of Artemia with or without ad libitum erosional site detritus. Growth was proportional to the mass of Artemia consumed, yet minnows showed increased growth with the detritus supplement at low invertebrate rations.
4. This study shows that detrital aggregate produced by decompositional processes at the erosional site could be nutritionally valuable to minnows. It appears that a feeding strategy of consuming detritus with a higher nutritional quality (i.e. detrital aggregate) as a dietary supplement benefits fishes in temperate as well as tropical systems.