Microstructural white matter integrity in relation to vascular reactivity in Dutch-type hereditary cerebral amyloid angiopathy

Cerebral Amyloid Angiopathy (CAA) is characterized by cerebrovascular amyloid-β accumulation leading to hallmark cortical MRI markers, such as vascular reactivity, but white matter is also affected. By studying the relationship in different disease stages of Dutch-type CAA (D-CAA), we tested the relation between vascular reactivity and microstructural white matter integrity loss. In a cross-sectional study in D-CAA, 3 T MRI was performed with Blood-Oxygen-Level-Dependent (BOLD) fMRI upon visual activation to assess vascular reactivity and diffusion tensor imaging to assess microstructural white matter integrity through Peak Width of Skeletonized Mean Diffusivity (PSMD). We assessed the relationship between BOLD parameters - amplitude, time-to-peak (TTP), and time-to-baseline (TTB) - and PSMD, with linear and quadratic regression modeling. In total, 25 participants were included (15/10 pre-symptomatic/symptomatic; mean age 36/59 y). A lowered BOLD amplitude (unstandardized β = 0.64, 95%CI [0.10, 1.18], p = 0.02, Adjusted R2 = 0.48), was quadratically associated with increased PSMD levels. A delayed BOLD response, with prolonged TTP (β = 8.34 × 10-6, 95%CI [1.84 × 10-6, 1.48 × 10-5], p = 0.02, Adj. R2 = 0.25) and TTB (β = 6.57 × 10-6, 95%CI [1.92 × 10-6, 1.12 × 10-5], p = 0.008, Adj. R2 = 0.29), was linearly associated with increased PSMD. In D-CAA subjects, predominantly in the symptomatic stage, impaired cerebrovascular reactivity is related to microstructural white matter integrity loss. Future longitudinal studies are needed to investigate whether this relation is causal.</p

FANCD1/BRCA2 Plays Predominant Role in the Repair of DNA Damage Induced by ACNU or TMZ

Nimustine (ACNU) and temozolomide (TMZ) are DNA alkylating agents which are commonly used in chemotherapy for glioblastomas. ACNU is a DNA cross-linking agent and TMZ is a methylating agent. The therapeutic efficacy of these agents is limited by the development of resistance. In this work, the role of the Fanconi anemia (FA) repair pathway for DNA damage induced by ACNU or TMZ was examined. Cultured mouse embryonic fibroblasts were used: FANCA−/−, FANCC−/−, FANCA−/−C−/−, FANCD2−/− cells and their parental cells, and Chinese hamster ovary and lung fibroblast cells were used: FANCD1/BRCA2mt, FANCG−/− and their parental cells. Cell survival was examined after a 3 h ACNU or TMZ treatment by using colony formation assays. All FA repair pathways were involved in ACNU-induced DNA damage. However, FANCG and FANCD1/BRCA2 played notably important roles in the repair of TMZ-induced DNA damage. The most effective molecular target correlating with cellular sensitivity to both ACNU and TMZ was FANCD1/BRCA2. In addition, it was found that FANCD1/BRCA2 small interference RNA efficiently enhanced cellular sensitivity toward ACNU and TMZ in human glioblastoma A172 cells. These findings suggest that the down-regulation of FANCD1/BRCA2 might be an effective strategy to increase cellular chemo-sensitization towards ACNU and TMZ

Evaluation of invasive and non-invasive methods for the diagnosis of Helicobacter pylori infection in symptomatic children and adolescents

CONTEXT: Multiple diagnostic methods are available for the detection of Helicobacter pylori infection, but at present no single one can be used as the gold standard. OBJECTIVE: The aim of this study was to evaluate the diagnostic accuracy of 3 invasive and 2 non-invasive methods for detection of Helicobacter pylori infection in symptomatic children and adolescents. DESIGN: Prospective cohort study SETTING: Peptic Disease outpatients service, Discipline of Pediatric Gastroenterology, Universidade Federal de São Paulo (UNIFESP) / Escola Paulista de Medicina. PATIENTS: Forty-seven patients who underwent endoscopy because of dyspeptic symptoms. DIAGNOSTIC METHODS: Endoscopy with gastric biopsies for 3 invasive (rapid urease test, histology and culture) and 2 non-invasive methods (a commercial ELISA serology and 13carbon urea breath test - isotope ratio mass spectrometry) for detection of Helicobacter pylori infection. MAIN MEASUREMENTS: Sensitivity, specificity, positive and negative predictive values of each method and agreement and disagreement rates between the methods. RESULTS: Forty-seven patients [mean age, 11y9mo (SD 2y10mo), 27 female and 20 male]; 62% of them were Helicobacter pylori-positive. All methods agreed in 61%, and were negative in 21% and positive in 40%. The greatest concordance between 2 methods occurred between the invasive methods: histology and rapid urease test (89.6%) and histology and culture (87.5%). The greatest sensitivity, considering Helicobacter pylori-positive cases, for any combination of 3 or more tests, was achieved by the rapid urease test (S=100%), followed by histology, serology and 13carbon-urea breath test (S=93.1%) and lastly by culture (S=79.3%). The highest specificity was obtained by histology (100%) and culture (100%), followed by the rapid urease test (84.2%), serology (78.9%) and 13carbon-urea breath test (78.9%). CONCLUSIONS: Our results suggest that among invasive methods, an association between the rapid urease test and histology constituted the best choice for the detection of Helicobacter pylori infection. If results of histology and the rapid urease test are different, serology may be recommended.CONTEXTO: Vários métodos diagnósticos estão disponíveis para a detecção da infecção por Helicobacter pylori (Hp), porém, até o presente momento, não há um teste que possa ser utilizado isoladamente como padrão-ouro. OBJETIVO: Avaliar a acurácia de três métodos invasivos e dois não-invasivos na detecção da infecção por Hp em crianças e adolescentes sintomáticos. TIPO DE ESTUDO: Estudo coorte prospectivo. LOCAL: Ambulatório de Doença Péptica, Disciplina de Gastroenterologia Pediátrica, Universidade Federal de São Paulo (UNIFESP) / Escola Paulista de Medicina. PACIENTES: 47 pacientes sintomáticos que realizaram exame endoscópico devido a sintomas dispépticos. MÉTODOS DIAGNÓSTICOS: Exame endoscópico com biopsias gástricas para três métodos invasivos (teste rápido da urease, histologia e cultura) e dois métodos não-invasivos (teste sorológico ELISA industrializado e teste respiratório com uréia marcada com Carbono13). VARIÁVEIS ESTUDADAS: Sensibilidade, especificidade, valor preditivo positivo e negativo de cada método e taxas de concordância e discordância entre os métodos. RESULTADOS: 47 pacientes [idade média de 11a9m (DP 2a10m), 27 do sexo feminino e 20 do masculino], 62% deles com infecção por Hp. Todos os 5 métodos concordaram em 61%, sendo negativo em 21% e positivo em 40%. As maiores concordâncias entre dois métodos ocorreram entre os métodos invasivos: histologia e teste rápido da urease (89,6%) e entre a histologia e cultura (87,5%). A maior sensibilidade, considerando como Hp positivo, qualquer combinação de 3 ou mais testes, foi encontrada no teste rápido da urease (S=100%), seguido pela histologia, sorologia e o teste respiratório com uréia marcada com Carbono13 (S=93,1%) e por fim a cultura (S=79,3%). A maior especificidade foi obtida pela histologia e cultura (100%), seguidos pelo teste rápido da urease (84,2%), sorologia (78,9%) e teste respiratório com uréia marcada com Carbono13 (78,9%). CONCLUSÕES: Nossos resultados sugerem que, entre os métodos invasivos, a associação do teste rápido da urease e histologia constituem a melhor escolha para a detecção da infecção por Hp. Se os resultados da histologia e do teste rápido da urease forem discordantes é recomendada a sorologia.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Pediatric DepartmentUNIFESP, EPM, Pediatric DepartmentSciEL

Plasticity of BRCA2 Function in Homologous Recombination: Genetic Interactions of the PALB2 and DNA Binding Domains

The breast cancer suppressor BRCA2 is essential for the maintenance of genomic integrity in mammalian cells through its role in DNA repair by homologous recombination (HR). Human BRCA2 is 3,418 amino acids and is comprised of multiple domains that interact with the RAD51 recombinase and other proteins as well as with DNA. To gain insight into the cellular function of BRCA2 in HR, we created fusions consisting of various BRCA2 domains and also introduced mutations into these domains to disrupt specific protein and DNA interactions. We find that a BRCA2 fusion peptide deleted for the DNA binding domain and active in HR is completely dependent on interaction with the PALB2 tumor suppressor for activity. Conversely, a BRCA2 fusion peptide deleted for the PALB2 binding domain is dependent on an intact DNA binding domain, providing a role for this conserved domain in vivo; mutagenesis suggests that both single-stranded and double-stranded DNA binding activities in the DNA binding domain are required for its activity. Given that PALB2 itself binds DNA, these results suggest alternative mechanisms to deliver RAD51 to DNA. In addition, the BRCA2 C terminus contains both RAD51-dependent and -independent activities which are essential to HR in some contexts. Finally, binding the small peptide DSS1 is essential for activity when its binding domain is present, but not when it is absent. Our results reveal functional redundancy within the BRCA2 protein and emphasize the plasticity of this large protein built for optimal HR function in mammalian cells. The occurrence of disease-causing mutations throughout BRCA2 suggests sub-optimal HR from a variety of domain modulations

Dyspepsia management in primary care

Background: Dyspepsia is common in western society. Prompt endoscopy is imperative in all patients with sinister symptoms or if symptoms first appear after the age of 50-55 years, but the optimal management of younger patients with uncomplicated dyspepsia is still open to debate. Methods: The literature on the management of uncomplicated dyspepsia is reviewed and a personal view is presented. Results: Strategies based on non-invasive detection of Helicobacter pylori are probably the most cost-effective. Currently (H. pylori prevalence 30%-40%), a 'test and treat' approach using a non-invasive test to detect H. pylori is likely to be the most efficient first step. If the patient is H. pylori-negative or if symptoms persist after successful H. pylori eradication, empirical treatment with an anti-secretory drug is justified. Endoscopy is reserved for those patients in whom this approach fails. If the prevalence of H. pylori decreases, the positive predictive value of any non-invasive H. pylori test will become too low. A 'test and scope' approach in which a positive test can be confirmed by two or more biopsy-based tests is then more appropriate. At a very low prevalence of H. Pylori in the dyspeptic population, non-invasive testing for H. pylori loses its significance and empirical treatment with an antisecretory drug becomes a rational first step. Conclusions: The optimal approach to management of uncomplicated dyspepsia is dependent on the prevalence of H. pylori among the dyspeptic population. At the current prevalence rate, 'test and treat', followed by acid suppressive treatment in the case of persisting symptoms, is the most appropriate strategy

Does the declining prevalence of Helicobacter pylori unmask patients with idiopathic peptic ulcer disease? Trends over an 8 year period

Objectives Recent studies have suggested that the prevalence of Helicobacter pylori infection in patients with ulcer disease who were not using non-steroidal anti-inflammatory drugs (NSAIDs) has been overestimated. The decreasing prevalence of H. pylori could lead to a relative increase in the number of patients with this idiopathic peptic ulcer disease (IPUD). This study aimed to investigate the prevalence of IPUD and any possible trends. Design and methods The reports of all upper gastrointestinal endoscopies performed in a Dutch regional hospital over the period 1991 to 1998 were reviewed. If a gastric and/or duodenal ulcer had been diagnosed, data concerning possible H. pylori infection (culture, histology, rapid in-house urease test) were retrieved. If H. pylori tests were negative, hospital files were examined for possible use of NSAIDs or other rare causes of ulcer disease. When these were not found, stored biopsy specimens were tested for H. heilmanii by using the polymerase chain reaction technique. Results Ulcer disease was diagnosed in 405 patients who had undergone endoscopy (1159 with gastric ulcer, 235 with duodenal ulcer, and 11 with both gastric and duodenal ulcer). H. pylori infection was found in 349 of these patients (86.2%). Thirty-three of the 56 H. pylori negative patients used NSAIDs and three patients had Crohn's disease, leaving 20 patients with IPUD (4.9%,12 gastric ulcer and eight duodenal ulcer). Time trends over the study period showed a decrease of H. pylori associated peptic ulcer disease (P <0.002) and an increase of NSAID associated peptic ulcer disease (P <0.0005). The prevalence of IPUD remained stable (P = 0.978). Conclusions The prevalence of patients with H. pylori negative ulcer disease significantly decreased in our study population due to an increase in the number of patients with NSAID associated peptic ulcer disease. IPUD was rare and its prevalence did not increase over a period of 8 years. (C) 2004 Lippincott Williams Wilkins

Nitroimidazole resistance in Helicobacter pylori

The efficacy of a nitroimidazole-containing regimen for the treatment of Helicobacter pylori infection is decreased by nitroimidazole resistance. Nitroimidazoles are metabolized by H. pylori by several nitro-reductases of which an oxygen-insensitive NADPH nitroreductase encoded by the rdxA gene is the most important. Null mutations in this gene are associated with resistance. Susceptibility testing to nitroimidazoles may give variable results. This is not only related to the slow growth under specific conditions, but also to variability in the activity of the other nitroreductases and the ability to deactivate toxic metabolites of an NI and to repair DNA damage. Moreover, co-infections with resistant and susceptible bacteria are frequently found. The presence of nitroimidazole resistance is related to the previous use of this drug. The prevalence of resistance is rising and nowadays 10-50% of the isolates are resistant. Resistance reduces the efficacy of a treatment regimen to a variable degree. This is related to efficacy of the other components of the regimen and the treatment duration. Whether a nitroimidazole is still effective in resistant strains remains unresolved. When nitroimidazole resistance is present, a nitro-imidazole-containing regimen should be avoided or a regimen with other highly effective components should be used

Six-year follow-up after successful triple therapy for Helicobacter pylori infection in patients with peptic ulcer disease

Objective & Design We question whether Helicobacter pylori eradication in peptic ulcer disease patients leads to a decrease in symptoms and reduced use of anti-dyspeptic drugs. Therefore, the recurrence rate of H. pylori, upper abdominal symptoms and the use of acid-suppressive drugs were determined 6 years after successful triple therapy. Methods Peptic ulcer disease patients successfully treated in 1990-1993 with 'classic' triple therapy were eligible. Patients were asked about symptoms and invited for a C-13-urea breath test or endoscopy in 1997-1998. Data on the use of anti-dyspeptic drugs were obtained from the pharmacy or general practitioner. Results Of the 113 eligible patients, 90 could be included in the study. The mean follow-up time was 6 years (range 4.6-7.6 years). H. pylori infection recurred in one patient (recurrence rate: 0.19% per patient-year; 95% confidence interval: 0.01-1.1%). Moderate or severe symptoms were experienced before therapy by 79% of the patients and after therapy by 18% of the patients (P <10-7). Before triple therapy, 98% of the patients used H-2-receptor antagonists and 54% were on maintenance treatment. 54% Conclusions Six years after successful triple therapy in peptic ulcer disease patients, the recurrence rate of H. pylori infection is low and both symptoms and the use of anti-dyspeptic drugs have decreased significantly. Eur J Gastroenterol Hepatol 13:1235-1239 (C) 2001 Lippincott Williams & Wilkins