Observation of Seven Astrophysical Tau Neutrino Candidates with IceCube

We report on a measurement of astrophysical tau neutrinos with 9.7 yr of IceCube data. Using convolutional neural networks trained on images derived from simulated events, seven candidate ν_{τ} events were found with visible energies ranging from roughly 20 TeV to 1 PeV and a median expected parent ν_{τ} energy of about 200 TeV. Considering backgrounds from astrophysical and atmospheric neutrinos, and muons from π^{±}/K^{±} decays in atmospheric air showers, we obtain a total estimated background of about 0.5 events, dominated by non-ν_{τ} astrophysical neutrinos. Thus, we rule out the absence of astrophysical ν_{τ} at the 5σ level. The measured astrophysical ν_{τ} flux is consistent with expectations based on previously published IceCube astrophysical neutrino flux measurements and neutrino oscillations.

A crosswalk of foundational BSN population health documents and the AACN essentials

To guide the development of entry-level nursing education, the American Association of Colleges of Nursing (AACN) published the Essentials document in 2021 with a broadened scope of competencies. Community, population, and public health (CPPH) nurse educators use a number of foundational documents to crosswalk for gaps in the AACN principles, highlighting the need of including these contemporary documents within the baccalaureate CPPH nursing curriculum. In this crosswalk, the authors highlight important capabilities and knowledge exclusive to these fundamental documents and tools, as well as the relevance of these competencies and knowledge to CPPH baccalaureate nursing education.

Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

Evidence for neutrino emission from the nearby active galaxy NGC 1068

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

eV-Scale Sterile Neutrino Search Using Eight Years of Atmospheric Muon Neutrino Data from the IceCube Neutrino Observatory

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100  eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5  eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100  TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100  TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100  TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

Time-Integrated Neutrino Source Searches with 10 Years of IceCube Data

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

Constraints on Minute-Scale Transient Astrophysical Neutrino Sources

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E^{-2.5} neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to <5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is <10^{52.5}  erg. For a harder E^{-2.13} neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is <10^{52}  erg. A hypothetical population of transient sources has to be more common than 10^{-5}  Mpc^{-3}  yr^{-1} (5×10^{-8}  Mpc^{-3}  yr^{-1} for the E^{-2.13} spectrum) to account for the complete astrophysical neutrino flux.

Search for neutrinos from decaying dark matter with IceCube: IceCube Collaboration

With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino 'track' events from the Northern Hemisphere, while the second analysis uses 2 years of 'cascade' events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than10 28 s at 90% CL for dark matter masses above 10 TeV .

Seasonal composition, abundance and biomass of the subestuarine fish assemblage in Solís Chico (Río de la Plata estuary, Uruguay)

Abstract The large estuaries can present long narrow branches called subestuaries or tidal creeks. These types of subsystems are distributed along the Uruguayan coast of the Río de la Plata estuary and are very important as nursery and refuge areas for fish. For the first time, the seasonal composition and abundance of the fish community of the Solís Chico subestuary was studied by using beach and gill nets. Fourteen species, mainly euryhaline (86%) presented a significant representation of juvenile stages. The fish community was dominated by Odontesthes argentinensis, Platanichthys platana, Mugil liza, Brevoortia aurea, Micropogonias furnieri and Paralichthys orbignyanus, similar to adjacent subestuaries. While Micropogonias furnieri and B. aurea were the most abundant species, some other species were rarely caught. A seasonal variation of the fish assemblage abundance was detected, with higher values in autumn showing a positive correlation with temperature. Species that complete their life cycle in the Río de la Plata estuary, some of which are relevant to fisheries (64% of the analyzed species) were captured in the Solís Chico subestuary. The importance of this environment as a transitional system for some estuarine fish species is advised.

Pathogenic Helicobacter pylori strains translocate DNA and activate TLR9 via the cancer-associated cag type IV secretion system

Helicobacter pylori is the strongest identified risk factor for gastric cancer, the third most common cause of cancer-related death worldwide. An H. pylori constituent that augments cancer risk is the strain-specific cag pathogenicity island, which encodes a type IV secretion system (T4SS) that translocates a pro-inflammatory and oncogenic protein, CagA, into epithelial cells. However, the majority of persons colonized with CagA⁺H. pylori strains do not develop cancer, suggesting that other microbial effectors also play a role in carcinogenesis. Toll-like receptor 9 (TLR9) is an endosome bound, innate immune receptor that detects and responds to hypo-methylated CpG DNA motifs that are most commonly found in microbial genomes. High expression tlr9 polymorphisms have been linked to the development of premalignant lesions in the stomach. We now demonstrate that levels of H. pylori-mediated TLR9 activation and expression are directly related to gastric cancer risk in human populations. Mechanistically, we show for the first time that the H. pylori cancer-associated cag T4SS is required for TLR9 activation and that H. pylori DNA is actively translocated by the cag T4SS to engage this host receptor. Activation of TLR9 occurs through a contact-dependent mechanism between pathogen and host, and involves transfer of microbial DNA that is both protected as well as exposed during transport. These results indicate that TLR9 activation via the cag island may modify the risk for malignancy within the context of H. pylori infection and provide an important framework for future studies investigating the microbial-epithelial interface in gastric carcinogenesis.

Nonhuman primate models for lymphoma, leukemia, and other neoplasms

Herpesvirus saimiri (HVS) is an oncogenic virus for a variety of nonhuman primates. HVS does not produce overt disease upon inoculation in the natural host (squirrel monkey) but consistently induces neoplasms including lymphomas and lymphocytic leukemias in 4 other species of monkeys. Various drugs inhibit replication of HVS in vitro including cytosine arabinoside and adenine arabinoside. In addition, the lymphoma and leukemia induced in owl monkeys responds to vincristine and prednisolone, cyclophosphamide, cytosine arabinoside, and human interferon. Of the various chemical carcinogens studied, the antitumor agent procarbazine induces neoplasms in a variety of species including monkeys. Thus far this compound has induced acute myelogenous leukemia (AML), lymphoma, and hemangiosarcomas in macaques. We have induced primary liver tumors in macaques with several nitrosamines and aflatoxin B1 and these tumors produce alpha-fetoprotein (AFP) which can be assayed for both diagnosis and therapy. Thus far, therapy of hepatocellular carcinoma has been most successful with surgical resection; and the tumor mass and serum AFP have been less responsive to single agent chemotherapy. These nonhuman primate models are useful for an understanding of the cause, diagnosis, prevention, and treatment of the human disease.

Sequential TPF chemotherapy followed by concurrent chemoradiotherapy in locally advanced head and neck cancer--a retrospective analysis of toxicity and outcomes

BACKGROUND AND AIMS

Phase III trials have shown that the addition of a taxane to cisplatin/5FU-based induction chemotherapy (TPF) improves response rates and overall survival in unresectable stage III/IV head and neck cancer. We sought to assess the tolerability, compliance and clinical outcomes of this treatment regime.

METHODS

A retrospective study of patients treated within a single centre between September 2007 and November 2010. Toxicities were graded according to CTCAE version 3.0. Survival, distant metastasis and local control rates are expressed as percentages at two years using the Kaplan-Meier method.

RESULTS

A total of 100 patients were identified (11% stage III, 86% stage IV) and 32% of patients were admitted as an emergency after TPF. The rate of neutropenic fever was 31%, this number fell to 9% when prophylactic G-CSF was used. In addition, 89% of patients underwent radical chemoradiation. Of these, 96% completed the full radiotherapy course. However, only 64% of patients received a minimum of two cycles of concurrent platinum chemotherapy. The two-year overall survival, metastasis free survival and local control rates were 62.6%, 88.5% and 73.3%, respectively.

CONCLUSIONS

TPF chemotherapy can be delivered safely in a non-trial cohort of patients. There is, however, a significant reduction in concurrent chemotherapy dose intensity. The long-term impact of this remains unclear.

Processed meat consumption and risk of cancer: a multisite case-control study in Uruguay

BACKGROUND

The role of processed meat in the aetiology of several cancers was explored in detail.

METHODS

In the time period 1996-2004, a multisite case-control study was conducted in Montevideo, Uruguay. The study included 6 060 participants (3 528 cases and 2 532 controls) corresponding to cancers of the oral cavity, pharynx, oesophagus, stomach, colon, rectum, larynx, lung, female breast, prostate, urinary bladder, and kidney (renal cell carcinoma only).

RESULTS

The highest odds ratios (ORs) were positively associated with cancers of the colon, rectum, stomach, oesophagus, and lung. With the exception of renal cell carcinoma, the remaining cancer sites were significantly associated with elevated risks for processed meat consumption. Furthermore, mortadella, salami, hot dog, ham, and salted meat were strongly associated with risk of several cancer sites.

CONCLUSION

It could be concluded that processed meat intake could be a powerful multiorgan carcinogen.

Vacuolating cytotoxin and variants in Atg16L1 that disrupt autophagy promote Helicobacter pylori infection in humans

BACKGROUND & AIMS

The Helicobacter pylori toxin vacuolating cytotoxin (VacA) promotes gastric colonization, and its presence (VacA(+)) is associated with more-severe disease. The exact mechanisms by which VacA contributes to infection are unclear. We previously found that limited exposure to VacA induces autophagy of gastric cells, which eliminates the toxin; we investigated whether autophagy serves as a defense mechanism against H pylori infection.

METHODS

We investigated the effect of VacA on autophagy in human gastric epithelial cells and primary gastric cells from mice. Expression of p62, a marker of autophagy, was also assessed in gastric tissues from patients infected with toxigenic (VacA(+)) or nontoxigenic strains. We analyzed the effect of VacA on autophagy in peripheral blood monocytes obtained from subjects with different genotypes of ATG16L1, which regulates autophagy. We performed genotyping for ATG16L1 in 2 cohorts of infected and uninfected subjects.

RESULTS

Prolonged exposure of human gastric epithelial cells and mouse gastric cells to VacA disrupted induction of autophagy in response to the toxin, because the cells lacked cathepsin D in autophagosomes. Loss of autophagy resulted in the accumulation of p62 and reactive oxygen species. Gastric biopsy samples from patients infected with VacA(+), but not nontoxigenic strains of H pylori, had increased levels of p62. Peripheral blood monocytes isolated from individuals with polymorphisms in ATG16L1 that increase susceptibility to Crohn's disease had reduced induction of autophagy in response to VacA(+) compared to cells from individuals that did not have these polymorphisms. The presence of the ATG16L1 Crohn's disease risk variant increased susceptibility to H pylori infection in 2 separate cohorts.

CONCLUSIONS

Autophagy protects against infection with H pylori; the toxin VacA disrupts autophagy to promote infection, which could contribute to inflammation and eventual carcinogenesis.

Mutagenic activity of nitrosated foods in an area with a high risk for stomach cancer

In a search for possible sources of mutagens in human foods, a study was made of six common foods in the diet of a population at high risk for gastric cancer (in Nariño, Colombia). No mutagenic activity was demonstrated in nonnitrosated foods. After nitrosation, only one of the foods, fava beans, demonstrated a mutagenic effect. This effect was direct and concentrated in the germ and pulp of the beans.

CagA C-terminal variations in Helicobacter pylori strains from Colombian patients with gastric precancerous lesions

The C-terminus of the Helicobacter pylori CagA protein is polymorphic, bearing different EPIYA sequences (EPIYA-A, B, C or D), and one or more CagA multimerization (CM) motifs. The number of EPIYA-C motifs is associated with precancerous lesions and gastric cancer (GC). The relationship between EPIYA, CM motifs and gastric lesions was examined in H. pylori-infected Colombian patients from areas of high and low risk for GC. Genomic DNA was extracted from H. pylori strains cultured from gastric biopsies from 80 adults with dyspeptic symptoms. Sixty-seven (83.8%) of 80 strains were cagA positive. The 3' region of cagA was sequenced, and EPIYA and CM motifs were identified. CagA proteins contained one (64.2%), two (34.3%) or three EPIYA-C motifs (1.5%), all with Western type CagA-specific sequences. Strains with one EPIYA-C motif were associated with less severe gastric lesions (non-atrophic and multifocal atrophic gastritis), whereas strains with multiple EPIYA-C motifs were associated with more severe lesions (intestinal metaplasia and dysplasia) (p <0.001). In 54 strains, the CM motifs were identical to those common in Western strains. Thirteen strains from the low-risk area contained two different CM motifs: one of Western type located within the EPIYA-C segment and another following the EPIYA-C segment and resembling the CM motif found in East Asian strains. These strains induced significantly shorter projections in AGS cells and an attenuated reduction in levels of CagA upon immunodepletion of SHP-2 than strains possessing Western/Western motifs. This novel finding may partially explain the difference in GC incidence in these populations.

OLGA staging for gastritis: a tutorial

Atrophic gastritis (resulting mainly from long-standing Helicobacter pylori infection) is a major risk factor for (intestinal-type) gastric cancer development and the extent/topography of the atrophic changes significantly correlates with the degree of cancer risk. The current format for histology reporting in cases of gastritis fails to establish an immediate link between gastritis phenotype and risk of malignancy. The histology report consequently does not give clinical practitioners and gastroenterologists an explicit message of use in orienting an individual patient's clinical management. Building on current knowledge of the biology of gastritis and incorporating experience gained worldwide by applying the Sydney System for more than 15 years, an international group of pathologists (Operative Link for Gastritis Assessment) has proposed a system for reporting gastritis in terms of stage (the OLGA staging system). Gastritis staging arranges the histological phenotypes of gastritis along a scale of progressively increasing gastric cancer risk, from the lowest (stage 0) to the highest (stage IV). This tutorial aims to provide unequivocal information on how to consistently apply the OLGA staging system in routine diagnostic histology practice.

CCL3L1 gene-containing segmental duplications and polymorphisms in CCR5 affect risk of systemic lupus erythaematosus

OBJECTIVES

There is an enrichment of immune response genes that are subject to copy number variations (CNVs). However, there is limited understanding of their impact on susceptibility to human diseases. CC chemokine ligand 3 like-1 (CCL3L1) is a potent ligand for the HIV coreceptor, CC chemokine receptor 5 (CCR5), and we have demonstrated previously an association between CCL3L1-gene containing segmental duplications and polymorphisms in CCR5 and HIV/AIDS susceptibility. Here, we determined the association between these genetic variations and risk of developing systemic lupus erythaematosus (SLE), differential recruitment of CD3+ and CD68+ leukocytes to the kidney, clinical severity of SLE reflected by autoantibody titres and the risk of renal complications in SLE.

METHODS

We genotyped 1084 subjects (469 cases of SLE and 615 matched controls with no autoimmune disease) from three geographically distinct cohorts for variations in CCL3L1 and CCR5.

RESULTS

Deviation from the average copy number of CCL3L1 found in European populations increased the risk of SLE and modified the SLE-influencing effects of CCR5 haplotypes. The CCR5 human haplogroup (HH)E and CCR5-Delta32-bearing HHG*2 haplotypes were associated with an increased risk of developing SLE. An individual's CCL3L1-CCR5 genotype strongly predicted the overall risk of SLE, high autoantibody titres, and lupus nephritis as well as the differential recruitment of leukocytes in subjects with lupus nephritis. The CCR5 HHE/HHG*2 genotype was associated with the maximal risk of developing SLE.

CONCLUSION

CCR5 haplotypes HHE and HHG*2 strongly influence the risk of SLE. The copy number of CCL3L1 influences risk of SLE and modifies the SLE-influencing effects associated with CCR5 genotypes. These findings implicate a key role of the CCL3L1-CCR5 axis in the pathogenesis of SLE.

Long term follow up of patients treated for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori infection induces progressive inflammatory changes in the gastric mucosa that may lead to gastric cancer. Understanding long term effects resulting from the cure of this infection is needed to design cancer prevention strategies.

METHODS

A cohort of 795 adults with preneoplastic gastric lesions was randomised to receive anti-H pylori treatment and/or antioxidants. At the end of six years of intervention, those who did not receive anti-H pylori treatment were offered it. Gastric biopsies were obtained at baseline, and at 3, 6, and 12 years. A histopathology score was utilised to document changes in gastric lesions. Non-linear mixed models were used to estimate the cumulative effect of H pylori clearance on histopathology scores adjusted for follow up time, interventions, and confounders.

RESULTS

Ninety seven per cent of subjects were H pylori positive at baseline, and 53% were positive at 12 years. Subjects accumulated 1703 person years free of infection. A multivariate model showed a significant regression in histopathology score as a function of the square of H pylori negative time. Subjects who were H pylori negative had 14.8% more regression and 13.7% less progression than patients who were positive at 12 years (p = 0.001). The rate of healing of gastric lesions occurred more rapidly as years free of infection accumulated, and was more pronounced in less advanced lesions.

CONCLUSIONS

Preneoplastic gastric lesions regress at a rate equal to the square of time in patients rendered free of H pylori infection. Our findings suggest that patients with preneoplastic gastric lesions should be treated and cured of their H pylori infection.

Gene expression in gastric biopsies from patients infected with Helicobacter pylori

BACKGROUND

Helicobacter pylori infection has protean effects on gene expression in the host gastric mucosa, which have been investigated by gene chip analysis in vitro. In this study the effects of H. pylori infection on host gene expression in the gastric antral mucosa in patients were examined.

METHODS

One gastric antral biopsy was obtained from a total of 18 untreated patients undergoing routine endoscopic evaluation of chronic abdominal complaints. Nine patients had histologic evidence of H. pylori infection and 9 age- and sex-matched patients had no histologic evidence of H. pylori infection. A microarray analysis was performed using a gene chip containing 35,000 human expressed sequence tags on RNA extracted from endoscopic, gastric antral biopsies, and average gene expression among infected and uninfected patients was compared.

RESULTS

Underexpressed genes in infected patients' mucosa included gastric intrinsic factor and several metallothionein isoforms. Overexpressed genes in infected patients' mucosa comprised MHC Class II molecules, immunoglobulin and B-cell activation genes, as well as genes known to induce apoptosis. Changes in expression were confirmed for a subset of genes by SYBR green real-time PCR.

CONCLUSIONS

Microarray analysis of antral biopsies from patients with and without H. pylori infection revealed differential expression of metal regulatory, immunity and inflammation-related genes.

Is gastric cancer preventable?

Gastric cancer is a major health burden worldwide and prevention is the most promising strategy to control the disease. The available scientific evidence indicates that curing Helicobacter pylori infection results in a modest retardation of the precancerous process but does not prevent all cancers. Individuals at the highest risk should be cured of their infection and monitored endoscopically to detect dysplasia and "early" cancer, amenable to successful treatment.

Therapeutic strategies in gastric cancer

Gastric cancer continues to be a major public health problem and is the second most common cause of cancer-related deaths in the world. These statistics led the American Society of Clinical Oncology (ASCO) International Affairs Committee to choose gastric cancer as the topic for the International Symposium held at the 2003 ASCO Annual Meeting. Dr Yoshiaki Ito will discuss the role of RUNX3 in the genesis and progression of human gastric cancer. Dr Pelayo Correa will present a compelling argument on the use of Helicobacter pylori therapy and antioxidants in selected high-risk population as chemoprevention strategies for gastric cancer. The controversy regarding the role of extended lymph node dissection for gastric cancer will be discussed by Dr Cornelis J.H. Van De Velde and Dr Mitsuru Sasako. Dr Van De Velde will present the European surgical approach to gastric cancer, and Dr Sasako will review the Japanese experience. The issues of whether certain patients benefit from more aggressive surgical dissection and the potential risks compared with benefits will also be discussed. Dr John Macdonald will discuss the role of adjuvant chemotherapy and adjuvant chemoradiotherapy in resected gastric cancer, as well as the role of chemotherapy in metastatic gastric cancer.

Food groups and risk of squamous cell carcinoma of the oesophagus: a case-control study in Uruguay

In the time period January 1998-December 2000, a case-control study on squamous cell cancer of the oesophagus was conducted in Montevideo, Uruguay. The main objective of the study was to estimate the odds ratios (ORs) associated with main food groups. For this purpose, 166 patients afflicted with squamous cell oesophageal cancer and 664 hospitalised controls were frequency matched on age and sex. Both series of patients were administered with a structured questionnaire. Aside from queries related with tobacco smoking, alcohol drinking and maté drinking, patients were interviewed with a food-frequency questionnaire (FFQ) on 64 items, representative of the usual Uruguayan diet. Red meat, salted meat and boiled meat displayed strong direct associations (OR for red meat 2.4, 95% CI 1.4-4.2). On the other hand, fish and total white meat showed moderate protective effect (OR for total white meat 0.5, 95% CI 0.3-0.9). Total fruit intake displayed a strong inverse association (OR 0.2, 95% CI 0.1-0.4), whereas total vegetable consumption presented a weak inverse association (OR for total vegetable intake 0.7, 95% CI 0.4-1.2). These results suggest that vegetables, mainly cooked vegetables, are rich in thermolabile protective substances. On the other hand, boiled (stewed) meat, which is ingested at high temperature could be, like maté, a risk factor for squamous cell cancer of the oesophagus.

Gastric mucosal atrophy: interobserver consistency using new criteria for classification and grading

BACKGROUND AND AIMS

Considerable difficulties persist amongst pathologists in agreeing on the presence and severity of gastric atrophy. An international group of pathologists pursued the following aims: (i) to generate an acceptable definition and a simple reproducible classification of gastric atrophy; and (ii) to develop guidelines for the recognition of atrophy useful for increasing agreement among observers.

METHODS

After redefining atrophy as the 'loss of appropriate glands' and examining histological samples from different gastric compartments, three categories were identified: (i) negative; (ii) indefinite; (iii) atrophy, with and without intestinalization. Atrophy was graded on a three-level scale. Interobserver reproducibility of the classification was tested by kappa statistics (general and weighted) in a series of 48 cases.

RESULTS

The medians of the general agreement and weighted kappa values were 0.78 and 0.73, respectively. The weighted kappa coefficients, obtained by cross-tabulating the evaluation of each pathologist against all others, were, with only one exception, > 0.4 (moderate to excellent agreement).

CONCLUSIONS

By using the definition of atrophy as the loss of appropriate glands and distinguishing the two main morphological entities of metaplastic and non-metaplastic types, a high level of agreement was achieved by a group of gastrointestinal pathologists trained in different cultural contexts.

Recombination and mutation during long-term gastric colonization by Helicobacter pylori: estimates of clock rates, recombination size, and minimal age

The bacterium Helicobacter pylori colonizes the gastric mucosa of half of the human population, resulting in chronic gastritis, ulcers, and cancer. We sequenced ten gene fragments from pairs of strains isolated sequentially at a mean interval of 1.8 years from 26 individuals. Several isolates had acquired small mosaic segments from other H. pylori or point mutations. The maximal mutation rate, the import size, and the frequency of recombination were calculated by using a Bayesian model. The calculations indicate that the last common ancestor of H. pylori existed at least 2,500-11,000 years ago. Imported mosaics have a median size of 417 bp, much smaller than for other bacteria, and recombination occurs frequently (60 imports spanning 25,000 bp per genome per year). Thus, the panmictic population structure of H. pylori results from very frequent recombination during mixed colonization by unrelated strains.

Morphometric evaluation of gastric antral atrophy: improvement after cure of Helicobacter pylori infection

OBJECTIVE

Our purpose was to find out if morphometric techniques can document long term changes in gastric antral atrophy after curing Helicobacter pylori infection with or without dietary supplementation with antioxidant micronutrients.

METHODS

Study subjects were 132 adult volunteers from a Colombian region with high gastric cancer rates. Participants were randomly assigned to ascorbic acid, beta-carotene, and anti-H. pylori treatment, following a factorial design. Gastric biopsies were obtained at baseline and after 72 months of intervention. Atrophy was evaluated by a standard visual analog scale and by morphometry.

RESULTS

Statistically significant changes in antral atrophy were detected with morphometric techniques after intervention in subjects who received anti-H. pylori treatment. A nonsignificant trend was also observed with visual scores. This effect was greater among those who were free of infection at the end of the trial. After accounting for the effect of anti-H. pylori treatment, no significant effect was noted for dietary supplementation with ascorbic acid and/or beta-carotene.

CONCLUSIONS

We conclude that gastric atrophy improves significantly after long term control of H. pylori infection. This effect can be demonstrated both by conventional histological grading and by morphometry.

The NeiI polymorphism in the cyclin D1 gene and sporadic primary hyperparathyroidism

OBJECTIVES

The cell cycle regulator cyclin D1 plays an important role in parathyroid tumourigenesis. The NciI polymorphism in exon 4 has recently been associated with early onset of hereditary nonpolyposis colorectal cancer and is a prognostic indicator of nonsmall cell lung cancer and squamous cell carcinomas. Furthermore, a limited study of 28 primary hyperparathyroidism (pHPT) patients displayed a tendency of NciI influence on HPT development. We hypothesized that the NciI polymorphism may relate to a risk of developing pHPT.

DESIGN, SETTING AND SUBJECTS

We genotyped 182 patients with sporadic pHPT and matched controls for the cyclin D1 polymorphism. A total of 88 pHPT patients and controls were recruited via a health-screening.

RESULTS

The frequency distribution of the NciI genotypes NN, Ni, and ii were in pHPT patients and controls 22, 44 and 34%, and 26, 49 and 25%, respectively. The calculated allele frequencies were A = 0.56; G = 0.44 in cases and A = 0.49; G = 0.51 in controls. The frequency distributions did not differ comparing cases and controls when subgrouped after age and menopausal status. The NciI genotypes were not significantly associated with age of the individuals, serum (s)-calcium, s-parathyroid hormone (PTH), bone mineral density (BMD) or parathyroid tumour weight in any of the groups of pHPT patients or controls.

CONCLUSIONS

No significant differences in distribution of the genotypes could be detected between the groups, suggesting that the polymorphism has minor or no pathogenic importance in the development of pHPT. Our results suggest that determination of the NciI polymorphism in the cyclin D1 gene is not a clinically useful tool for prediction of pHPT.

Morphometric assessment of gastric antral atrophy: comparison with visual evaluation

AIMS

As part of a multinational effort to reach a consensus in the definition and evaluation of atrophic gastritis, we applied morphometric techniques to 22 antral biopsy specimens examined visually by 12 experienced gastrointestinal pathologists.

METHODS AND RESULTS

Atrophy was defined as loss of glands. Each pathologist graded atrophy with both non-standardized and standardized approaches. Discriminant function analyses of morphometric measurements were conducted to validate and grade atrophy. Kappa statistics were used to compare the performance of each pathologist against the group mode and against the discriminant functions' grading of atrophy. Three morphometric indexes showed significant differences among categories of atrophy utilizing non-standardized as well as standardized visual atrophy grades: (i) the ratio of glandular length to total mucosal thickness; (ii) the proportion of the secretory compartment area occupied by glands; and (iii) the number of glandular cross sections per 40x microscopic field. The discriminant function analyses verified all cases classified visually as either non-atrophic, or moderately/severely atrophic; it verified as mildly atrophic 40% of the cases classified visually as mildly atrophic; and classified the remaining 60% as moderately or severely atrophic. The kappa statistics were good or excellent for the majority of pathologists.

CONCLUSIONS

The evaluation of antral atrophy, simply defined as loss of glands, can be reliable and reproducible. The visual grading of atrophy as absent, moderate and severe is entirely consistent with objective morphometric observations.

The effect of vaccination with the PAV-250 strain classical swine fever (CSF) virus on the airborne transmission of CSF virus

The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as the effect of vaccination with the CSF virus PAV-250 strain was investigated on this mode of transmission. Experiment I: four pigs were inoculated with the ALD CSFV strain (10(4.3) 50% TCID) by the intramuscular route, and at the onset of fever, they were introduced into an enclosed chamber. At the end of the experiment surviving pigs were sedated, anesthetized and euthanatized. Experiment II: four pigs were previously vaccinated with the CSF virus PAV-250 strain, and at 14 days post-vaccination they were challenged with the CSF virus ALD strain. In both experiments, four susceptible pigs were exposed to infectious aerosols by placing them in a chamber connected by a duct to the adjacent pen containing the infected animals and were kept there for 86 hs. In Experiment I, pigs exposed to contaminated air died as a result of infection with CSF virus on days 14, 21 and 28 post-inhalation. These four pigs seroconverted from day 12 post-inhalation. CSF virus was isolated from these animals, and the fluorescent antibody test on tonsils was positive. In Experiment II, a vaccinated pig exposed to contaminated air did not seroconvert, nor was CSF virus isolated from lymphoid tissues. However, mild fluorescence in tonsil sections from these pigs was observed. In conclusion, CSF virus was shown to be transmitted by air at a distance of 1 m to susceptible pigs. Vaccination with the PAV-250 CSF virus strain protected the pigs from clinical disease under the same conditions.

Plant foods and risk of gastric cancer: a case-control study in Uruguay

The association between plant foods intake and gastric cancer risk was investigated in a Uruguayan study on environmental factors and cancer. The study included 160 newly diagnosed and histologically verified cases of gastric carcinoma and 320 hospitalized controls. These controls were frequency-matched to the cases on age, sex, residence and urban/rural status. Total vegetable intake was associated with a reduction in risk (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.38-1.08), which was markedly attenuated after adjustment for total fruit intake. The only group of vegetables that persisted as significantly protective after controlling for total energy and total fruit consumption were allium vegetables (OR 0.56, 95% CI 0.34-0.92). On the other hand, total fruit consumption displayed a strong inverse association after controlling for total vegetable intake (OR 0.35, 95% CI 0.21-0.59). Neither tubers nor pulses were associated with gastric cancer risk. Finally, total plant foods were strongly associated with a reduced risk of stomach cancer (OR 0.31, 95% CI 0.18-0.54). It is suggested that vitamins (vitamin C and carotenoids) and bioactive substances (diallyl sulfide) could be involved in the mechanisms of action of plant foods.