Attenuated amyloid-beta aggregation and neurotoxicity owing to methionine oxidation

Aggregation of the amyloid-beta (Abeta) peptide into amyloid plaques is a characteristic feature of Alzheimer's disease neuropathogenesis. We and others have previously demonstrated delayed Abeta aggregation as a consequence of oxidizing a single methionine residue at position 35 (Met-35). Here, we examined the consequences of Met-35 oxidation on the extremely aggregation-prone peptides Abeta1-42 and Abeta1-40Arctic with respect to protofibril and oligomer formation as well as neurotoxicity. Size exclusion chromatography and mass spectrometry demonstrated that monomer/dimers prevailed over larger oligomers after oxidizing Met-35, and consequently protofibril formation and aggregation of both Abeta1-42 and Abeta1-40Arctic were delayed. The oxidized peptides completely lacked neurotoxic effects in cortical neuronal cultures under these conditions, in contrast to the neurotoxic properties of the unoxidized peptides. We conclude that oxidation of Met-35 significantly attenuates aggregation of Abeta1-42 and Abeta1-40Arctic, and thereby reduces neurotoxicity.     

Immunogenicity and reactogenicity of two diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio virus-Haemophilus influenzae type b vaccines administered at 3, 5 and 11-12 months of age

The use of combination vaccines in the routine childhood program reduces distress to the recipients and is likely to improve uptake rates and timeliness of vaccination but requires careful evaluation and surveillance. The aim of this study was to evaluate the immunogenicity and reactogenicity of two commercial diphtheria-tetanus- acellular pertussis-hepatitis b-inactivated polio virus-Haemophilus influenzae type b (DTaP-HBV-IPV/Hib) combination vaccines when administered to infants at 3, 5 and 11-12 months of age. A total of 494 infants were randomized to receive three doses of either Infanrix hexa (GlaxoSmithKline Biologicals; N = 246) or Hexavac (Sanofi Pasteur MSD; N = 248) in 10 centers in Italy, Finland and Sweden. After the third dose, antibodies to diphtheria, tetanus, polio and Hib were at the protective level in nearly all infants in both groups whereas the proportion of subjects who had achieved the protective concentration of >or=10 mIU/ml to hepatitis B surface antigen was 99.1% (95% CI 96.7-99.9) in the Infanrix hexa group as compared to 94.4% (95% CI 90.4.97.1) in the Hexavac group. Antibody titers to all three polio antigens were highest in Italy and lowest in Finland. Clinically relevant general reactions (such as fever of >39.5 degrees C) were mostly reported in less than 5% of the vaccinees. Three doses of DTaP-HBV-IPV/Hib combination vaccines produced sufficient immune responses in nearly all vaccinees.     

Gut Toxicity During Hemopoietic Stem Cell Transplantation May Predict Acute Graft-Versus-Host Disease Severity in Patients

Graft-versus-host disease (GVHD) is the primary complication of allogeneic, hemopoietic, stem cell transplantation (HSCT). Murine models suggest that gut toxicity, induced by the intensive chemotherapy preceding hematopoietic stem cell infusion, aggravates systemic GVHD. In HSCT patients gut toxicity correlates with chemotherapy intensity. The present study investigates acute GVHD severity and intestinal toxicity in patients undergoing allogeneic HSCT. In 38 patients intestinal permeability was assessed before and after chemotherapy (on days −1, +4, +7 and +14 as related to the stem cell infusion). Cumulative acute GVHD (days 0–100) and clinical intestinal toxicity (days 0–14) were evaluated in parallel. Patients with mild, acute GVHD (grades 0–I) had better-preserved intestinal barrier function (P=0.04) and less pronounced cumulative clinical intestinal toxicity (P=0.02) compared with patients with more severe acute GVHD (grades II–IV). Gut toxicity predicts acute GVHD severity. Therefore, gut protective strategies may diminish GVHD severity in allogeneic HSCT patients.     

Human combinatorial libraries yield rare antibodies that broadly neutralize hepatitis C virus

One way to dissect the antibody response to an invading microorganism is to clone the antibody repertoire from immune donors and subsequently characterize the specific antibodies. Recently, methodological advances have allowed investigations of neutralizing antibodies against hepatitis C virus (HCV) in vitro. We have investigated three human mAbs, previously isolated from an individual infected with HCV of genotype 2b, that are known to cross-react in a binding assay to the envelope E2 protein of genotypes 1a and 1b. We now report that two of them have a neutralizing activity with a breadth not previously observed. Indeed, mAbs 1:7 and A8 recognized E2 from all of the six major genotypes, and they neutralized retroviral pseudoparticles [HCV pseudoparticles (HCVpp)] carrying genetically equally diverse HCV envelope glycoproteins. Importantly, these antibodies were also able to neutralize the cell culture infectious HCV clone JFH-1 in vitro, with IC(50) values of 60 ng/ml and 560 ng/ml, respectively. The conformational epitopes of these two broadly reactive antibodies were overlapping yet distinct and involved amino acid residues in the 523-535 region of E2, known to be important for the E2-CD81 interaction. The third antibody clone, representing a dominant population in the initial screen for these antibodies, was less broadly reactive and was unable to neutralize the genotype 2a infectious clone JFH-1. Our results confirm at the clonal level that broadly neutralizing human anti-HCV antibodies can be elicited and that the region amino acids 523-535 of the HCV envelope glycoprotein E2 carries neutralizing epitopes conserved across all genotypes.     

Poor prognosis in carcinoma is associated with a gene expression signature of aberrant PTEN tumor suppressor pathway activity

Pathway-specific therapy is the future of cancer management. The oncogenic phosphatidylinositol 3-kinase (PI3K) pathway is frequently activated in solid tumors; however, currently, no reliable test for PI3K pathway activation exists for human tumors. Taking advantage of the observation that loss of PTEN, the negative regulator of PI3K, results in robust activation of this pathway, we developed and validated a microarray gene expression signature for immunohistochemistry (IHC)-detectable PTEN loss in breast cancer (BC). The most significant signature gene was PTEN itself, indicating that PTEN mRNA levels are the primary determinant of PTEN protein levels in BC. Some PTEN IHC-positive BCs exhibited the signature of PTEN loss, which was associated to moderately reduced PTEN mRNA levels cooperating with specific types of PIK3CA mutations and/or amplification of HER2. This demonstrates that the signature is more sensitive than PTEN IHC for identifying tumors with pathway activation. In independent data sets of breast, prostate, and bladder carcinoma, prediction of pathway activity by the signature correlated significantly to poor patient outcome. Stathmin, encoded by the signature gene STMN1, was an accurate IHC marker of the signature and had prognostic significance in BC. Stathmin was also pathway-pharmacodynamic in vitro and in vivo. Thus, the signature or its components such as stathmin may be clinically useful tests for stratification of patients for anti-PI3K pathway therapy and monitoring therapeutic efficacy. This study indicates that aberrant PI3K pathway signaling is strongly associated with metastasis and poor survival across carcinoma types, highlighting the enormous potential impact on patient survival that pathway inhibition could achieve.     

Improved vascular engraftment and function of autotransplanted pancreatic islets as a result of partial pancreatectomy in the mouse and rat

Aims/hypothesis The few patients subjected to autotransplantation of pancreatic islets after pancreatectomy usually become normoglycaemic after using islets from the resected organ only, whereas allogeneic recipients usually require at least two grafts to retain normoglycaemia. Previous experimental studies have demonstrated that islets transplanted to non-pancreatectomised recipients acquire a markedly decreased blood vessel density, which leads to a hypoxic microenvironment. The aim of the present study was to test the hypothesis that autotransplanted islets have better vascular engraftment and function as a result of the pancreatic surgery involved. Materials and methods In the present study, athymic mice and inbred rats were subjected to a 60% pancreatectomy and transplanted with human or rat islets, respectively, 4 days later. Control animals underwent sham surgery. Blood flow, oxygen tension, vascular density and endocrine volume in the islet grafts were measured 1 month after transplantation. Separate grafts were used for perfusion experiments and for assessment of beta cell proliferation and endocrine cellular apoptosis at different time periods after transplantation. Results Islet grafts in partially pancreatectomised recipients had an increased blood flow, oxygen tension, blood vessel density and endocrine mass 1 month post-transplantation compared with control animals. They also exhibited increased insulin release in perfusion experiments performed 1 month post-transplantation, and decreased cellular apoptosis early after transplantation. Conclusions/interpretation The present study shows that the pancreatectomy procedure itself has beneficial effects on the engraftment of transplanted human and rat islets. Our results provide an additional explanation, besides diminished immunological responses, of the much better outcome of islet autotransplantations compared with allogeneic transplantations in the clinic.     

Prevalence of oesophageal eosinophils and eosinophilic oesophagitis in adults: the population-based Kalixanda study

BACKGROUND: Eosinophilic oesophagitis may be increasing but the prevalence in the general population remains unknown. Our aim was to assess this and the presence of eosinophils in the distal oesophageal epithelium in the community. METHODS: Oesophagogastroduodenoscopy was performed in a random sample (n = 1000) of the adult Swedish population (mean age 54 years, 49% men). Oesophageal biopsy samples were obtained from 2 cm above, and at, the Z-line. Any eosinophil infiltration of the epithelium was defined as "eosinophils present". Definite eosinophilic oesophagitis was defined as > or =20, probable as 15-19, and possible as 5-14 eosinophils/high-power field (HPF, at magnification x 40) in oesophageal biopsy specimens. RESULTS: Eosinophils were present in 48 subjects (4.8%, 95% CI 3.5 to 6.1%, mean age 54 years, 63% men), in 54% without troublesome reflux symptoms. Definite eosinophilic oesophagitis was present in four subjects (0.4%, 95% CI 0.01 to 0.8%, mean age 51 years, 75% men) and probable eosinophilic oesophagitis in seven subjects (0.7%, 95% CI 0.2 to 1.2%, mean age 58 years, 43% men). Erosive oesophagitis (OR = 2.99, 95% CI 1.58 to 5.66) and absence of dyspepsia (OR = 0.23, 95% CI 0.07 to 0.75) and Helicobacter pylori infection (OR = 0.41, 95% CI 0.19 to 0.92) were independent predictors for "eosinophils present". Definite eosinophilic oesophagitis was associated with dysphagia (2/66 vs 2/926, p = 0.025), and probable eosinophilic oesophagitis with narrowing of the oesophageal lumen (2/15 vs 5/978, p = 0.005). CONCLUSIONS: Oesophageal eosinophils were present in nearly 5% of the general population; approximately 1% had definite or probable eosinophilic oesophagitis. Oesophageal eosinophils may be a manifestation of reflux disease in adults, but the condition is as likely to be asymptomatic and go unrecognised.     

The risk of myocardial infarction and sudden cardiac death amongst snuff users with or without a previous history of smoking

Objectives. To investigate the risk of a first myocardial infarction (MI) and sudden cardiac death (SCD) amongst male snuff users. Design. We used a prospective incident case‐referent study design nested in the population‐based Västerbotten Intervention Program and the Northern Sweden MONICA study. Subjects. Tobacco habits and cardiovascular risk factors were assessed at baseline screening and compared in 525 male MI cases (including 93 SCD cases) and 1798 matched referents. Results. Myocardial infarction occurred on average 4 years and 2 months after the baseline screening. No increased risk for MI was found amongst snuff users without a previous history of smoking compared with nontobacco users after adjustments for body mass index, leisure time physical activity, educational level and cholesterol level (OR 0.82; 95% CI, 0.46–1.43). For snuff users with a previous history of smoking, the adjusted OR was 1.25 (95% CI, 0.80–1.96). Significantly increased risk for MI was found in current smokers with or without current snuff use. For SCD cases with survival time <24 h, the adjusted OR for snuff users without previous history of smoking was 1.18 (95% CI, 0.38–3.70) and for cases with survival time <1 h the OR was 0.38 (95% CI, 0.08–1.89). Conclusions. We found no increased risk for MI amongst snuff users without a previous history of smoking. Amongst snuff users with a previous history of smoking, the tendency towards an increased risk for MI may reflect the residual risk from former smoking. This study does not support the hypothesis that the risk for SCD is increased amongst snuff users.