Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

Background

Numerous studies have reported that age-induced increased parathyroid hormone plasma levels are associated with cognitive decline and dementia. Little is known about the correlation that may exist between neurological processing speed, cognition and bone density in cases of hyperparathyroidism. Thus, we decided to determine if parathyroid hormone levels correlate to processing speed and/or bone density.

Methods

The recruited subjects that met the inclusion criteria (n = 92, age-matched, age 18-90 years, mean = 58.85, SD = 15.47) were evaluated for plasma parathyroid hormone levels and these levels were statistically correlated with event-related P300 potentials. Groups were compared for age, bone density and P300 latency. One-tailed tests were used to ascertain the statistical significance of the correlations. The study groups were categorized and analyzed for differences of parathyroid hormone levels: parathyroid hormone levels <30 (n = 30, mean = 22.7 ± 5.6 SD) and PTH levels >30 (n = 62, mean = 62.4 ± 28.3 SD, p ≤ 02).

Results

Patients with parathyroid hormone levels <30 showed statistically significantly less P300 latency (P300 = 332.7 ± 4.8 SE) relative to those with parathyroid hormone levels >30, which demonstrated greater P300 latency (P300 = 345.7 ± 3.6 SE, p = .02). Participants with parathyroid hormone values <30 (n = 26) were found to have statistically significantly higher bone density (M = -1.25 ± .31 SE) than those with parathyroid hormone values >30 (n = 48, M = -1.85 ± .19 SE, p = .04).

Conclusion

Our findings of a statistically lower bone density and prolonged P300 in patients with high parathyroid hormone levels may suggest that increased parathyroid hormone levels coupled with prolonged P300 latency may become putative biological markers of both dementia and osteoporosis and warrant intensive investigation.     

High temporal and inter‐individual variation detected in the human ileal microbiota

The diversity and temporal stability of the predominant bacteria in the human ileum was studied with the use of ileal effluent samples of seven individuals with Brooke ileostomies. The total number of bacteria within the ileal effluent was in the range of 10⁷–10⁸ bacteria per gram (wet weight). The diversity of the bacteria in the ileal effluent showed marked differences compared with that in faecal samples from age‐matched healthy adults. The ileal effluent had a higher relative abundance of species within the orders Lactobacillales and Clostridiales, mainly Streptococcus bovis‐related species, and the Veillonella group, and a lower proportion of species related to Ruminococcus gnavus, R. obeum and Bacteroides plebeius. In addition, inter‐individual differences were found, indicative of a highly personal ileal microbiota profile. Furthermore, temporal profiles showed large fluctuations per individual over a period of 9–28 days (average similarity over a period of 9 days was as low as 44%), and differences between morning and afternoon profiles were observed. Parallel cloning and sequencing efforts revealed several phylotypes that were not identified in previous studies (12 out of 65 phylotypes showed less than 97% sequence similarity with previously reported sequences). Achaea were found to be below detection limit by quantitative PCR. Overall, the results indicate that the microbiota of the human ileum is relatively unstable, less complex and consisting of different dominating phylotypes when compared with the colonic microbiota.     

Concurrent hexachlorobenzene and chloroethene transformation by endogenous dechlorinating microorganisms in the Ebro River sediment

The ability of Dehalococcoides spp. to reduce chlorinated compounds offers a great potential for bioremediation and/or bioaugmentation of contaminated environments. So far, however, our knowledge of the activity of Dehalococcoides spp. in situ is limited to only a few subsurface environments. The aim of this study was to broaden this knowledge to other environments, and we investigated the role of Dehalococcoides spp. in the transformation of chlorinated benzenes and chlorinated ethenes in the Ebro River (Spain) sediments. Lab-scale batch microcosms were used to follow the growth and abundance of Dehalococcoides spp. during the transformation of selected chlorinated compounds. We applied biomolecular tools targeting the 16S rRNA, the 16S rRNA gene and several functional genes involved in dechlorination in combination with chemical measurements. The growth of Dehalococcoides spp. and the differential expression of several reductive dehalogenase genes during the dechlorination process could be demonstrated. Furthermore, 16S rRNA gene-based clone libraries of dechlorinating river sediment showed a complex community structure and indicated the involvement of several additional bacterial genera in the transformation process, underlining the remarkable potential of this rivers' sediment to transform different halo-organic pollutants.     

Microbial Community Development in a Dynamic Gut Model Is Reproducible,Colon Region Specific,and Selective for Bacteroidetes and Clostridium Cluster IX

Dynamic, multicompartment in vitro gastrointestinal simulators are often used to monitor gut microbial dynamics and activity. These reactors need to harbor a microbial community that is stable upon inoculation, colon region specific, and relevant to in vivo conditions. Together with the reproducibility of the colonization process, these criteria are often overlooked when the modulatory properties from different treatments are compared. We therefore investigated the microbial colonization process in two identical simulators of the human intestinal microbial ecosystem (SHIME), simultaneously inoculated with the same human fecal microbiota with a high-resolution phylogenetic microarray: the human intestinal tract chip (HITChip). Following inoculation of the in vitro colon compartments, microbial community composition reached steady state after 2 weeks, whereas 3 weeks were required to reach functional stability. This dynamic colonization process was reproducible in both SHIME units and resulted in highly diverse microbial communities which were colon region specific, with the proximal regions harboring saccharolytic microbes (e.g., Bacteroides spp. and Eubacterium spp.) and the distal regions harboring mucin-degrading microbes (e.g., Akkermansia spp.). Importantly, the shift from an in vivo to an in vitro environment resulted in an increased Bacteroidetes/Firmicutes ratio, whereas Clostridium cluster IX (propionate producers) was enriched compared to clusters IV and XIVa (butyrate producers). This was supported by proportionally higher in vitro propionate concentrations. In conclusion, high-resolution analysis of in vitro-cultured gut microbiota offers new insight on the microbial colonization process and indicates the importance of digestive parameters that may be crucial in the development of new in vitro models.The human gastrointestinal tract harbors a complex microbial ecosystem with a coding capacity exceeding that of the host genome by a factor of 100 (13). These gut microbes play a determining role in host health by converting otherwise indigestible compounds (14, 19), protecting against gut epithelial cell injury (46), regulating host fat storage (49), and inducing immunity (20, 48). Modulation of the composition and metabolic activity of these microbes to improve host health attracts a lot of attention and is referred to as gastrointestinal resource management (15, 37). Such new strategies are often evaluated during human trials or in vivo studies of animals associated with conventional or human microbiota (50).Despite the physiological relevance, in vivo experimental setups are inherently associated with some drawbacks. First, apart from fecal analyses over time, most in vivo data are derived from endpoint measurements, thereby limiting the dynamic monitoring of the gut microbiota. Second, troublesome sampling of different gut regions makes it difficult to locate the effects of a treatment. For mechanistic reasons, a third drawback of an in vivo approach is the inability to focus solely on gut microbial activity, because there is always a host involved. For these reasons, different types of in vitro systems have been developed, ranging from simple nonstirred batch cultures without pH control (44) to more complex continuous models involving pH-controlled single (55) or dynamic multicompartment (2, 29, 32, 34) culture systems. Other advantages are the lack of ethical constraints and a higher reproducibility due to strict control of environmental factors that can influence the microbiota, such as retention time, pH, temperature, and food intake. Therefore, in vitro methods are widely used to elucidate the mechanism behind the degradation of prebiotics (17, 52), bioactivation of polyphenols (10, 36, 38), adhesion of microbes to mucins (51), or bioavailability of environmental contaminants (53, 54).Dynamic in vitro gut models need to fulfil certain criteria before they can be used to monitor the modulating potency of specific treatments toward the microbiota. To ensure that effects are due solely to the treatment and not to the adaptation of microbes to the in vitro environment, steady-state conditions in terms of microbial community composition and metabolic activity need to be established prior to the actual start of the experiment (39). Moreover, the stabilization of this in vitro microbiota needs to be reproducible, as comparison of different treatments requires identical starting communities. Former studies assumed but never fully substantiated this requirement (17, 38). Further, in vitro microbiota need to be gut region specific, be representative for the in vivo situation, and maintain a high diversity. The potency of in vitro models thus relies on a good characterization of its microbiota. Molecular techniques, such as denaturing gradient gel electrophoresis (DGGE) (17, 39, 52), fluorescent in situ hybridization (FISH) (6), and quantitative real-time PCR (Q-PCR) (17, 29), provide useful information but do not provide direct phylogenetic information or target only a limited group of previously identified organisms, therefore limiting current knowledge. Recently, high-resolution techniques, such as microarrays (41, 42) and pyrosequencing (59), have provided access to phylogenetic and metagenomic analysis of the gut microbiota in unprecedented detail.In this study, we performed conventional metabolic analysis, applied existing molecular techniques (DGGE), and for the first time provided an in-depth phylogenetic analysis on the simulator of the human intestinal microbial ecosystem (SHIME) in vitro microbiota using the recently developed human intestinal tract chip (HITChip) microarray (41, 42). We evaluated the microbial colonization process in two parallel in vitro simulators (Twin-SHIME) simultaneously inoculated with the same human fecal microbiota. The aims of this study were (i) to determine when the microbial community composition and metabolic activity reach steady-state conditions, (ii) to assess the reproducibility of the stabilization process in two identical in vitro simulators, (iii) to obtain a high-resolution characterization of the colon region specificity of the residing communities, and (iv) to evaluate how the in vivo fecal inoculum changes to the in vitro colon microbial communities.     

Real-time PCR: housekeeping genes in the INS-1E beta-cell line.

Investigation of gene expression is a developing area with several methods available. One method is quantitative PCR. A major pitfall in quantitative PCR is the normalisation procedure of the gene expression. Many experiments include a housekeeping gene, some use RNA concentration, and others use a geometric mean of several internal, stably expressed genes. This study demonstrates that real-time-PCR results differ with varying housekeeping genes and analysis protocols when applied to insulin-secreting INS-1E cells derived from the pancreas and stimulated by DEDTC (diethyldithiocarbamate, a zinc chelator) and GLP-1.     

Degradation of Methanethiol by Methylotrophic Methanogenic Archaea in a Lab-Scale Upflow Anaerobic Sludge Blanket Reactor

In a lab-scale upflow anaerobic sludge blanket reactor inoculated with granular sludge from a full-scale wastewater treatment plant treating paper mill wastewater, methanethiol (MT) was degraded at 30°C to H₂S, CO₂, and CH₄. At a hydraulic retention time of 9 h, a maximum influent concentration of 6 mM MT was applied, corresponding to a volumetric loading rate of 16.5 mmol liter⁻¹ day⁻¹. The archaeal community within the reactor was characterized by anaerobic culturing and denaturing gradient gel electrophoresis analysis, cloning, and sequencing of 16S rRNA genes and quantitative PCR. Initially, MT-fermenting methanogenic archaea related to members of the genus Methanolobus were enriched in the reactor. Later, they were outcompeted by Methanomethylovorans hollandica, which was detected in aggregates but not inside the granules that originated from the inoculum, the microbial composition of which remained fairly unchanged. Possibly other species within the Methanosarcinacaea also contributed to the fermentation of MT, but they were not enriched by serial dilution in liquid media. The archaeal community within the granules, which was dominated by Methanobacterium beijingense, did not change substantially during the reactor operation. Some of the species related to Methanomethylovorans hollandica were enriched by serial dilutions, but their growth rates were very low. Interestingly, the enrichments could be sustained only in the presence of MT and did not utilize any of the other typical substrates for methylotrophic methanogens, such as methanol, methyl amine, or dimethylsulfide.     

Seed bank,biomass, and productivity of Halophila decipiens, a deep water seagrass on the west Florida continental shelf

One of the largest contiguous seagrass ecosystems in the world is located on the shallow continental shelf adjacent to the west coast of Florida, USA and is comprised of seasonally ephemeral Halophila decipiens meadows. Little is known about the demography of the west Florida shelf H. decipiens, which may produce 4.56 × 10⁸ g C day⁻¹ or more during the peak growing season. We documented seagrass distribution, biomass, and productivity, and density of sediment seed reserves, seedlings, flowers and fruits on the southeastern portion of the west Florida shelf by sampling along a transect at three stations in 10, 15, and 20 m water depth. Biomass, flower, fruit, seedling, and seed bank densities tended to be highest at stations in 10–15 m water depth and lowest at 20 m. Flowers and fruit were most prevalent during summer cruises (June and August 1999, July 2000). Seedling germination occurred during summer, fall (October 1999), and winter (January 2000) sampling events, with the highest seedling densities present during the winter. Seed bank density remained consistent through time. A Category I hurricane with sustained winds of 120 km h⁻¹ passed over the stations, but only limited impact on H. decipiens biomass was observed. The presence of a persistent seed bank provides for recovery after storm disturbance, annual reestablishment of populations, and continual maintenance of the 20,000 km² of deep water seagrass habitat present on the west Florida shelf.     

Influence of the gastrointestinal microbiota on development of the immune system in young animals

The gastrointestinal tract (GIT) of adult mammals is colonized by a complex and dynamic community of microorganisms. Most protection against potential pathogens occurs via a mucosal immune system involving mechanisms of innate immunity as well as a secondary lymphoid organ, the gut-associated lymphoid tissue (GALT). However, the bacterial community also supports its host against invasion by potential pathogens, by a mechanism called 'colonization resistance'. Young animals need time to develop both a complex bacterial community and their immature GIT immune system, and until such developments have taken place, they are vulnerable to the presence of potential pathogens in their GIT. Initial protection against invading pathogens is provided by milk and colostrum, which contain antibodies and other bioactive components. At weaning, with the introduction of solid food and deprivation of the mother's milk, the young must also cope with a rapidly changing microbiota. The colonizing microbiota not only provides colonization resistance to potentially pathogenic bacteria. It also has a major role in the development of the intestinal immune system, both in terms of GALT development and mucosal immunity, and the induction of oral tolerance. Studies using gnotobiotic animal models have revealed that the presence of even limited numbers of the indigenous microbiota may influence the GIT immune system. Regulation of the composition of the GIT microbiota, e.g. by the use of pre- and probiotics, offers the possibility to influence the development of mucosal, and also systemic immunity.