The incidence of Helicobacter pylori acquisition in children of a Canadian First Nations community and the potential for parent-to-child transmission

BACKGROUND AND AIMS: We have previously reported that Wasagamack, a Canadian First Nations community has a seroprevalence rate of Helicobacter pylori of 95% and a prevalence rate among children aged 0-12 years as measured by stool antigen testing of 56%. We aimed to determine the rate of infection acquisition and possible modes of transmission of childhood Helicobacter pylori infection in this Canadian First Nations community. METHODS: Children who were previously negative for H. pylori by stool antigen testing in August 1999 were eligible for enrollment in August 2000; 50 (77%) eligible children underwent stool collection. H. pylori stool antigen status was tested using the Premier Platinum HpSA test. Drinking water samples, maternal saliva, breast milk, local berries and flies were tested by three complementary H. pylori-specific PCR assays. Soothers or bottle nipples, collected from 16 children whose H. pylori stool antigen status was determined, were bathed in sterile water and this water was tested by PCR. RESULTS: Stool was positive for H. pylori in 16% (8/ 50) of children retested. Five had no other siblings infected and three had infected siblings. The mothers of all children infected were positive for H. pylori. The median age of newly infected children was 6 years (range 1-13 years). By PCR, 78% (18/23) mothers' saliva samples, 69% (11/16) soother water samples and 9% (1/11) water samples from infected homes tested positive. All of 24 sequenced PCR-produced DNA fragments from samples showed 99% homology with that from ATCC type strain H. pylori. CONCLUSIONS: The rate of childhood H. pylori acquisition was 16% over 1 year, and was not dependent on number of siblings infected. The finding of homologous H. pylori DNA in saliva and in soother water suggests the possibility of human to human transmission, particularly via an oral-oral route. Thus, there is the potential for further investigations in this population and other endemic communities that are directed at prevention of infection transmission via this modality.     

Epigenetics: a landscape takes shape

Epigenetics has recently evolved from a collection of diverse phenomena to a defined and far-reaching field of study. In this Essay, we examine the epistemology of epigenetics, provide a brief overview of underlying molecular mechanisms, and suggest future challenges for the field.     

Optogenetics and thermogenetics: technologies for controlling the activity of targeted cells within intact neural circuits

In recent years, interest has grown in the ability to manipulate, in a temporally precise fashion, the electrical activity of specific neurons embedded within densely wired brain circuits, in order to reveal how specific neurons subserve behaviors and neural computations, and to open up new horizons on the clinical treatment of brain disorders. Technologies that enable temporally precise control of electrical activity of specific neurons, and not these neurons' neighbors-whose cell bodies or processes might be just tens to hundreds of nanometers away-must involve two components. First, they require as a trigger a transient pulse of energy that supports the temporal precision of the control. Second, they require a molecular sensitizer that can be expressed in specific neurons and which renders those neurons specifically responsive to the triggering energy delivered. Optogenetic tools, such as microbial opsins, can be used to activate or silence neural activity with brief pulses of light. Thermogenetic tools, such as thermosensitive TRP channels, can be used to drive neural activity downstream of increases or decreases in temperature. We here discuss the principles underlying the operation of these two recently developed, but widely used, toolboxes, as well as the directions being taken in the use and improvement of these toolboxes.     

The small-subunit processome is a ribosome assembly intermediate

The small-subunit (SSU) processome is a large ribonucleoprotein required for the biogenesis of the 18S rRNA and likely corresponds to the terminal knobs visualized by electron microscopy on the 5' end of nascent rRNAs. The original purification of the SSU processome of Saccharomyces cerevisiae resulted in the identification of 28 proteins. Here, we characterize 12 additional protein components, including five small-ribosomal-subunit proteins (Rps4, Rps6, Rps7, Rps9, and Rps14) that had previously been copurified. Our multiple criteria for including a component as a bona fide SSU processome component included coimmunoprecipitation with Mpp10 (an SSU processome component), the U3 snoRNA, and the anticipated pre-rRNAs. Importantly, the association of specific ribosomal proteins with the SSU processome suggests that the SSU processome has roles in both pre-rRNA processing and ribosome assembly. These ribosomal proteins may be analogous to the primary or secondary RNA binding proteins first described in bacterial in vitro ribosome assembly maps. In addition to the ribosomal proteins and based on the same experimental approach, we found seven other proteins (Utp18, Noc4, Utp20, Utp21, Utp22, Emg1, and Krr1) to be bona fide SSU processome proteins.     

Assembly of thick filaments and myofibrils occurs in the absence of the myosin head

We investigated the importance of the myosin head in thick filament formation and myofibrillogenesis by generating transgenic Drosophila lines expressing either an embryonic or an adult isoform of the myosin rod in their indirect flight muscles. The headless myosin molecules retain the regulatory light-chain binding site, the alpha-helical rod and the C-terminal tailpiece. Both isoforms of headless myosin co-assemble with endogenous full-length myosin in wild-type muscle cells. However, rod polypeptides interfere with muscle function and cause a flightless phenotype. Electron microscopy demonstrates that this results from an antimorphic effect upon myofibril assembly. Thick filaments assemble when the myosin rod is expressed in mutant indirect flight muscles where no full-length myosin heavy chain is produced. These filaments show the characteristic hollow cross-section observed in wild type. The headless thick filaments can assemble with thin filaments into hexagonally packed arrays resembling normal myofibrils. However, thick filament length as well as sarcomere length and myofibril shape are abnormal. Therefore, thick filament assembly and many aspects of myofibrillogenesis are independent of the myosin head and these processes are regulated by the myosin rod and tailpiece. However, interaction of the myosin head with other myofibrillar components is necessary for defining filament length and myofibril dimensions.     

Amniotic fluid and plasma glycine/valine ratios in substrate deprived growth retarded fetal rats.

Characteristic profiles of the free amino acid concentration in umbilical cord blood of growth retarded newborns have been observed. We hypothesized that the amniotic fluid of growth retarded fetal rats would show an increase in the ratio between glycine and valine which would parallel the pattern observed in the cord blood of growth retarded neonates, thus providing an index for the antepartum identification of the substrate deprived growth retarded fetus. Six test and 6 control dams were tested. Four fetuses per dam, matched for uterine location were examined. Test animals were fasted for 72 hours. Sampling was performed on day 21 under anaesthesia. Fetal size was significantly reduced (P < 0.0001) in the test group. [T = 2.68 gs. +/- 0.28 vs. C = 3.67 gs. +/- 0.25]. Fetal plasma concentrations of glycine showed an increase in test animals (P < 0.01) while valine showed a significant reduction (P < 0.0001). Glycine (pm/microliters) T = 308 +/- 64 vs. C = 269 +/- 47, valine (pm/microliters) T = 424 +/- 79 vs. C = 671 +/- 218]. Amniotic fluid concentrations for both glycine and valine were significantly decreased (P < 0.0001) in test animals. [Glycine (pm/microliters) T = 710 +/- 124 vs. C = 931 +/- 178; valine (pm/microliters) T = 845 +/- 169 vs. C = 1,339 +/- 234]. The glycine/valine ratio was significantly increased (P < 0.01) in both fetal plasma and amniotic fluid in test animals [Plasma T = 0.74 +/- 0.18 vs. C = 0.43 +/- 0.13. Amniotic fluid T = 0.85 +/- 0.08 vs. C = 0.69 +/- 0.09]. Consistent with our hypothesis, the amniotic fluid concentrations generally parallel the observations made in the plasma. This finding could enhance the antepartum identification of the substrate deprived growth retarded fetus.     

Tumor promotion resistant cells are deficient in AP-1 DNA binding, JunD DNA binding and JunD expression and form different AP-1-DNA complexes than promotion sensitive cells

The JB6 cell culture model is used to identify molecular determinants of susceptibility to the promotion of neoplastic transformation. Clonal variants susceptible to transformation ('P+' cells) form numerous anchorage-independent colonies in soft agar upon treatment with the phorbol ester tumor promoter TPA, whereas resistant variants ('P-' cells) do not. We now report that there is significantly less binding of activator protein-1 (AP-1) to its DNA binding site in P- cells than in P+ cells. Gel supershift assays were performed to detect association of all seven AP-1 family members with their DNA binding site in TPA-treated and -untreated P+ and P- cells. Significantly lower DNA binding and protein expression of JunD were detected in P- cells than in P+ cells. c-Jun was detected in P+, but not P-, AP-1-DNA complexes, and c-Fos was detected in P-, but not P+, AP-1-DNA complexes. These and other phenotype-specific differences in abundance and composition of AP-1-DNA complexes may play a role in the resistance of P- cells to tumor promoter-induced transformation.