The Duisburg birth cohort study: influence of the prenatal exposure to PCDD/Fs and dioxin-like PCBs on thyroid hormone status in newborns and neurodevelopment of infants until the age of 24 months

Prenatal exposure to polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can affect neurobehavioral development of infants and children. This effect may be mediated through disruption of thyroid hormone homeostasis. However, epidemiological studies reveal no consistent influence of PCDD/Fs and PCBs on thyroid status and neurodevelopment at environmental background levels. The effects may resolve with time of further decreasing exposure to these compounds. The aim of this study was to find out if there are still effects related to prenatal PCDD/F and PCB observable at the meanwhile decreased levels of exposure by using the same methods which have been applied in similar studies during the last 10 years in Europe. The birth cohort study was initiated in the year 2000 in the industrialized city of Duisburg, Germany. 232 healthy mother-infant pairs were recruited between 2000 and 2002. Dioxins, dioxin-like PCBs and six indicator PCBs were analyzed in maternal blood during pregnancy and in maternal milk following extraction and sample clean-up by HRGC/HRMS. Thyroid stimulating hormone (TSH), total thyroxine (T4), total triiodothyronine (T3), free thyroxine (FT4) and free triiodothyronine (FT3) were measured in serum samples of the pregnant women and in cord serum samples by chemiluminescent immunometric assay. Neurological examinations were performed at ages 2 weeks and 18 months using the neurological optimality score (NOS), mental and motor development were assessed using the Bayley Scales of Infant Development (BSID) at ages 12 and 24 months. Multiple linear regression analysis was used to describe the association of PCDD/F and PCB in maternal blood or milk with the outcome measurements after adjustment for confounding. Blood levels (n=182) of WHO 2005 toxic equivalents (TEQ) (PCDD/F+PCB) were in the range of 3.8-58.4 pg/glipid base (median: 19.3 pg/glipid base). The corresponding data for human milk (n=149) were 2.6-52.4 pg/glipid base (median: 19.7 pg/glipid base). Multiple regression analysis showed no decrease of thyroid hormones related to WHO 2005 TEQ in blood and milk of mothers and their newborns. Furthermore, no associations between exposure and neurological and developmental measures were observed. This study supports the view that the current decreased exposure to PCDD/Fs and PCBs does not impair thyroid function of newborns and neurodevelopment of infants until the age of 24 months.     

Dynamic spatial coding within the dorsal frontoparietal network during a visual search task

To what extent are the left and right visual hemifields spatially coded in the dorsal frontoparietal attention network? In many experiments with neglect patients, the left hemisphere shows a contralateral hemifield preference, whereas the right hemisphere represents both hemifields. This pattern of spatial coding is often used to explain the right-hemispheric dominance of lesions causing hemispatial neglect. However, pathophysiological mechanisms of hemispatial neglect are controversial because recent experiments on healthy subjects produced conflicting results regarding the spatial coding of visual hemifields. We used an fMRI paradigm that allowed us to distinguish two attentional subprocesses during a visual search task. Either within the left or right hemifield subjects first attended to stationary locations (spatial orienting) and then shifted their attentional focus to search for a target line. Dynamic changes in spatial coding of the left and right hemifields were observed within subregions of the dorsal front-parietal network: During stationary spatial orienting, we found the well-known spatial pattern described above, with a bilateral hemifield representation in the right hemisphere and a contralateral preference in the left hemisphere. However, during search, the right hemisphere had a contralateral preference and the left hemisphere equally represented both hemifields. This finding leads to novel perspectives regarding models of visuospatial attention and hemispatial neglect.     

Pharmacokinetic genes do not influence response or tolerance to citalopram in the STAR*D sample

Background

We sought to determine whether clinical response or tolerance to the Selective Serotonin Reuptake Inhibitor (SSRI) citalopram is associated with genetic polymorphisms in potentially relevant pharmacokinetic enzymes.

Methodology

We used a two-stage case-control study design in which we split the sample of 1,953 subjects from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial into a discovery (n = 831) and validation set (n = 1,046). Fifteen polymorphisms from five (CYP2D6, ABCB1, CYP2C19, CYP3A4, and CYP3A5) pharmacokinetic genes were genotyped. We examined the associations between these polymorphisms and citalopram response and tolerance. Significant associations were validated in the second stage for those polymorphism found to be statistically significant in the first stage.

Conclusions

No genetic polymorphism in the pharmacokinetic genes examined was significantly associated with our response or tolerance phenotypes in both stages. For managing pharmacological treatment with citalopram, routine screening of the common pharmacokinetic DNA variants that we examined appears to be of limited clinical utility.     

Vegetation control effects on untreated wood,crude cellulose and holocellulose δ<Superscript>13</Superscript>C of early and latewood in 3- to 5-year-old rings of Douglas-fir

The stable carbon (C) composition of tree rings expressed as δ¹³C, is a measure of intrinsic water-use efficiency and can indicate the occurrence of past water shortages for tree growth. We examined δ¹³C in 3- to 5-year-old rings of Douglas-fir (Pseudotsuga menziesii (Mirb) Franco) trees to elucidate if decreased water supply or uptake was a critical factor in the observed growth reduction of trees competing with understory herb and shrub vegetation compared to those growing without competition. We hypothesized that there would be no differences in δ¹³C of earlywood in trees growing in plots with competing vegetation and those in plots receiving complete vegetation control during 5 years because earlywood formed early in the growing season when soil water was ample. We also hypothesized that δ¹³C in latewood which was formed during the later half of the growing season when precipitation was low, would be greater (less negative) in trees in plots without vegetation control. We then separated early and latewood from rings for three consecutive years and analyzed their δ¹³C composition. No significant differences in earlywood δ¹³C in years 3–5 were observed for trees in the two vegetation control treatments. δ¹³C of untreated latewood separated from wood cores was greater in 4- and 5-year-old rings of trees growing with competing vegetation compared to trees growing without vegetation competition (i.e., −25.5 vs. −26.3‰ for year 4, and −26.1 vs. −26.8‰ for year 5). Results suggest that water shortages occurred in Douglas-fir trees on this coastal Washington site in the latewood-forming portion of the growing season of years 4 and 5 in the no-vegetation control treatment. We also compared δ¹³C from untreated wood, crude cellulose extracted with the Diglyme–HCl method, and holocellulose extracted with toluene–ethanol to see if the extraction method would increase the sensitivity of the analysis. δ¹³C values from the two extraction methods were highly correlated with those from untreated samples (r ² = 0.97, 0.98, respectively). Therefore, using untreated wood would be as effective as using crude cellulose or holocellulose to investigate δ¹³C patterns in young Douglas-fir.     

The <Emphasis Type="Italic">Helicobacter pylori mutY</Emphasis> homologue HP0142 is an antimutator gene that prevents specific C to A transversions

Extensive genetic variability resulting from a high mutation rate and frequent recombination is a characteristic of Helicobacter pylori. Its average mutation rate is 1 × 10⁻⁶, similar to that of Escherichia coli mutator strains. Few genes involved in DNA repair have been functionally characterized in H. pylori. In E. coli, the DNA glycosylase MutY is a part of the base excision repair system. The H. pylori mutY homolog HP0142 was analyzed in this study. HP0142 was disrupted by inserting a kanamycin resistance cassette. Mutation rates were determined by measuring the frequency of point mutations in rpoB conferring resistance against rifampicin. Inactivation of mutY in H. pylori resulted in an increase of the mutation frequency by a factor of up to 34. Sequence analysis of rpoB in rifampicin-resistant clones selected from the mutY mutant showed a modest increase of G:C/T:A transversions in comparison to clones selected from wild type strains. In contrast, inactivation of mutY had a profound impact on the distribution of mutations within rpoB. This finding suggests that the efficiency with which mutY prevents transversions is strongly dependent upon the sequence context. Inactivation of mutY was associated with a stationary phase fitness deficit in competitive cultures with the wild type strain.     

Characterization of sequence determinants within the carboxyl-terminal domain of chemokine receptor CCR5 that regulate signaling and receptor internalization.

The CC chemokine receptor CCR5 mediates chemotaxis of leukocytes and serves as a principal co-receptor for macrophage-tropic human immunodeficiency virus type 1. To identify determinants on the CCR5 carboxyl-terminal domain that regulate receptor signaling and internalization, we generated several CCR5 mutants, which were progressively shortened from the COOH terminus or had carboxyl-terminal serine, cysteine, or leucine residues substituted by alanine and expressed them in RBL-2H3 cells. Using fluorescence resonance energy transfer between beta-arrestin and CCR5 tagged with cyan and yellow variants of green fluorescent protein, we show that high affinity association of the two molecules in living cells requires intact carboxyl-terminal serine phosphorylation sites. Phosphorylation-deficient truncation or Ser/Ala replacement mutants of CCR5 mediated a sustained calcium response and enhanced granular enzyme release in RANTES-stimulated cells. Carboxyl-terminal serine residues are critically involved in CCR5 endocytosis and a dileucine motif, similar to that implicated in the regulation of CXCR2 and CXCR4, contributes to the internalization of CCR5 in a phosphorylation-independent manner. Despite their prominent role in receptor desensitization and internalization, beta-arrestins are dispensable for the CCR5-mediated stimulation of mitogen-activated protein kinase pathways in RBL-2H3 cells. We also show that CCR5 is palmitoylated on carboxyl-terminal cysteine residues. Inhibition of CCR5 palmitoylation by alanine mutagenesis of cysteines or treatment with a palmitate analogue inhibitor profoundly reduces phorbol 12-myristate 13-acetate- and RANTES-induced receptor phosphorylation, homologous desensitization, and internalization. Alanine mutagenesis of serine, cysteine, or leucine residues or the limited carboxyl-terminal truncation of CCR5 did not impair chemokine-stimulated migration of RBL-2H3 cells. Together these results indicate that post-translational modifications of carboxyl-terminal serine and cysteine residues have a significant impact on receptor deactivation and internalization.     

Compartment analysis of T cell receptor gamma--and immunoglobulin V(H) rearrangements by microdissection in patients with malt lymphoma and chronic gastritis with lymphatic hyperplasia.

The interpretation of clonality within H. pylori-associated gastritis and low-grade MALT lymphoma remains controversial. Due to the observation of MALT lymphoma regression after H. pylori eradication, new definitions concerning the border between benign reactive lesions and malignant gastric lymphoma are needed. Gene rearrangements for immunoglobulin heavy-chain in low-grade MALT lymphoma (N= 12) and H. pylori-associated chronic gastritis with lymphatic hyperplasia (N= 13) were analyzed by microdissection and polymerase chain reaction. Furthermore, T cell receptor-gamma chain rearrangements were analyzed by gene scan analysis. In 11 of 12 cases with initial low-grade MALT lymphoma, intraepithelial and subepithelial B cell rearrangements showed a restricted usage of the immunoglobulin heavy-chain 3. In H. pylori-associated chronic gastritis, the intraepithelial B cell compartment showed an oligoclonal the immunoglobulin heavy-chain rearrangement pattern with a predominance of VH3. The subepithelial compartment did not show any restrictive immunoglobulin heavy-chain gene usage. Additionally a mono- to oligoclonal rearrangement pattern of the T cell receptor-y chain was observed in low-grade MALT lymphoma, whereas an oligoclonal pattem was observed in chronic gastritis. Our data provide evidence that low-grade MALT lymphoma may start within the epithelium and subsequently infiltrate the subepithelial compartment. The observation of a mono- to oligoclonal TCR-gamma rearrangement suggests that an antigen selecting process also takes place within reactive T cells. Combining TCR-gamma gene scan analysis with IgH chain rearrangement analysis might help in discriminating between chronic gastritis and initial MALT lymphoma in questionable cases.     

When is a family not a family?

Recent molecular investigations of the small-subunit rRNA gene sequences have indicated that established taxonomic hierarchies can be clearly at odds with the degree of evolutionary divergence (as inferred from molecular divergence) between supposedly equivalent taxa at every rank (i.e., species through class), both within and across biological divisions. This is particularly true between the Rhodophyta and the Phaeophyta, whose higher-order taxa appear under- and overinflated, respectively. We present two plausible alternatives that algal taxonomists might adopt in order to invoke discussion on their relative merits.     

DEUCALION GEN. NOV. AND ANISOSCHIZUS GEN. NOV. (CERAMIACEAE,CERAMIALES), TWO NEW PROPAGULE-FORMING RED ALGAE FROM SOUTHERN AUSTRALIA1

Two new propagule-farming red algae from southern Australia, Deucalion levringii (Lindauer) gen. et comb. nov. and Anisoschizus propaguli gen. et sp. nov., are described and defined largely on their development in laboratory culture. Deucalion is included in the tribe Compsothamnieae on the basis of its subapical procarp and alternate distichous branching. It differs from the other genera included in that tribe in that it produces 3-celled propagules, polysporangia, a subapical cell of the fertile axis which bears 3 pericentral cells, and an apparently post-fertilization involucre which develops from the hypogenous and sub-hypogenous cells of the fertile axis. Its gametophyte morphology has been elucidated in culture, as only sporophytes are known from the field. Gametophytes do not appear to produce propagules. Anisoschizus is provisionally included in the tribe Spermothamnieae on the basis of its subdichotomous branching, possession of a prostrate system and the production of polysporangia. It differs from the other genera of the tribe in the production of 2-celled propagules. Observations on the germination of the “monosporangia” of Mazoyerella arachnoidea and Monosporus spp. indicate that they are analagous to the propagules of Deucalion and Anisoschizus. The nature of these propagules and their role in recycling the parent plant are discussed and contrasted with true monosporangia. It is recommended that Monosporus be maintained as a form genus containing representatives from more than one tribe, as exemplified by plants from Lord Howe I. provisionally identified as M. indicus Boergesen which have both prostrate and erect, as opposed to only erect, axes.     

Radiorespirometric studies of carbohydrate metabolism by washed spermatozoa of various species.

1. The patterns of 14CO2 evolution from specifically labeled glucose substrates by washed bull, ram, boar, rabbit, dog, rooster and turkey spermatozoa were similar and indicated the Embden-Meyerhof and Kreb's cycle pathways as the major route of energy metabolism. 2. Honey bee spermatozoa metabolized glucose-3,4-[14C], glucose-[U-14C] or fructose-[U-14C], but not glucose-1-[14C], glucose-2-[14C]or glucose-6-[14C], indicating the presence of the glycolytic pathway, but the absence of respiration via the Kreb's cycle. 3. The rate of glycolysis exceeded the rate of respiration in the spermatozoa of all the species studied. 4. A preferential utilization of glucose-1-[14C] over glucose-6-[14C] was evident in some sperm samples, but no consistent indication of pentose cycle metabolism was observed, due to considerable variability between samples within each group. 5. Fructose metabolism was greater than glucose metabolism in the rooster, less in the dog, boar and turkey, and similar in the spermatozoa from the other species examined. 6. Only ram and bull spermatozoa metabolized acetate-1-[14C] to any extent.