Putative Precursor Cancer Cells in Human Colorectal Cancer Tissue

Multistage carcinogenesis is an important concept in cancer biology. Each new stage is triggered by the acquisition of an additional genetic aberration, leading to clonal expansion of the cancer cell. The resulting tumor mass consists of cancer cells with all genetic aberrations, but may include precursor cells at some point of carcinogenesis. We analyzed six colorectal cancer tissues with APC, K-ras, and p53 mutations. From each sample, 40–50 areas (100×100×40μm) consisting only of cancer cells were microdissected, and genomic DNA was purified. Ratios of mutated and normal alleles were quantitated by the SNaPshot assay, a primer extension assay. In five tumor tissues, we identified cancer cell subpopulations corresponding to putative precursors, i.e., cells with mutations in one or two of the three genes. All samples were likely to be of monoclonal origin, and temporal sequences of the mutations could be deduced from the mutation patterns of putative precursors. The orders of mutation events were variable. However, the two carcinoma tissues accompanying adenoma regions started with the APC mutation, not contradicting the previous studies. The analysis also revealed considerable heterogeneity in allele ratios of one or two of the chromosomes. The current findings are promising to uncover the process of carcinogenesis directly from the tumor tissue of the patient.     

Bilateral recession of superior rectus muscles: Its influence on A and V pattern strabismus

PURPOSE: To determine whether bilateral superior rectus recession modifies A and V pattern strabismus. PATIENTS AND METHODS: Three patients with V patterns and eight patients with A patterns underwent bilateral superior rectus recession with neither oblique muscle surgery nor vertical displacement of the horizontal rectus muscles. Another three patients with A patterns underwent simultaneous superior oblique tenotomy and superior oblique recession. RESULTS: Two of the patients with V patterns demonstrated an increase in the V pattern after surgery; one was unchanged. Five of the patients with A patterns converted to V patterns after surgery. In the remaining three patients the pattern was eliminated. The three patients who underwent superior oblique tenotomy along with superior rectus recession had large shifts toward V pattern (mean shift, 40 delta). CONCLUSION: Bilateral superior rectus recession tends to increase V patterns and reduce A patterns. Superior rectus recession may be synergistic with superior oblique tenotomy in collapsing an A pattern.     

Oxidative stress: Predictive marker for coronary artery disease

The role of oxidative stress in cardiovascular disease processes, such as atherogenesis, ischemic-reperfusion injury and cardiac remodelling, has been increasingly recognized in the past few decades. Currently, an increasing number of studies suggest that levels of oxidative stress markers in body fluids correlate with atherosclerotic disease activity. This finding may lead to novel clinical approaches in patients with coronary artery disease. Assessment of oxidative stress markers could modify risk stratification and treatment of patients with suspected coronary artery disease or myocardial infarction.     

Founder effect of the Glu89Gln TTR mutation in the Bulgarian population

Abstract

Hereditary transthyretin amyloidosis is an autosomal dominant genetic disorder caused by missense mutations in the TTR gene resulting in amyloid formation of the transthyretin protein. Depending on the system affection, the manifestations may be different and high heterogeneity in the penetrance is observed. An endemic region in Bulgaria exists where the TTR mutation Glu89Gln is found with high frequency. This is a rare mutation and was probably introduced in the population by a common ancestor. This phenomenon, called “founder effect” was proved in carrier families by haplotype analysis of microsatellite markers showing linkage disequilibrium. Allele frequencies were analyzed and haplotype reconstruction was done with Arlequin v.3.01 software. The common ancestry of the carriers was demonstrated using additional data for their genealogies and microsatellite data from a control group of non-affected individuals. The results show that the mutation Glu89Gln is linked to one haplotype, called “hypothetical founder haplotype” which was compared to published haplotype data from other European patients and no similarity was found. Further population genetics studies of carriers of the Glu89Gln mutation from other endemic regions are required in order to clarify the geographical distribution of the mutation.     

Multi-platform genotoxicity analysis of silver nanoparticles in the model cell line CHO-K1

Investigation of the genotoxic potential of nanomaterials is essential to evaluate if they pose a cancer risk for exposed workers and consumers. The Chinese hamster ovary cell line CHO-K1 is recommended by the OECD for use in the micronucleus assay and is commonly used for genotoxicity testing. However, studies investigating if this cell line is suitable for the genotoxic evaluation of nanomaterials, including induction of DNA adduct and micronuclei formation, are rare and for silver nanoparticles (Ag NPs) missing. Therefore, we here systematically investigated DNA and chromosomal damage induced by BSA coated Ag NPs (15.9 ± 7.6 nm) in CHO-K1 cells in relation to cellular uptake and intracellular localization, their effects on mitochondrial activity and production of reactive oxygen species (ROS), cell cycle, apoptosis and necrosis. Ag NPs are taken up by CHO-K1 cells and are presumably translocated into endosomes/lysosomes. Our cytotoxicity studies demonstrated a concentration-dependent decrease of mitochondrial activity and increase of intracellular reactive oxygen species (ROS) in CHO-K1 cells following exposure to Ag NPs and Ag⁺ (0–20 μg/ml) for 24 h. Annexin V/propidium iodide assay showed that Ag NPs and Ag⁺ induced apoptosis and necrosis, which is in agreement with an increased fraction of cells in subG1 phase of the cell cycle. Genotoxicity studies showed that Ag NPs but also silver ions (Ag⁺) induced bulky-DNA adducts, 8-oxodG and micronuclei formation in a concentration-dependent manner, however, there were quantitative and qualitative differences between the particulate and ionic form of silver. Taken together, our multi-platform genotoxicity and cytotoxicity analysis demonstrates that CHO-K1 cells are suitable for the investigation of genotoxicity of nanoparticles like Ag NPs.     

Abacavir Hypersensitivity Reaction Reporting Rates During a Decade of HLA-B*5701 Screening as a Risk-Mitigation Measure

Introduction

Human leukocyte antigen (HLA)-B*5701 screening identifies patients at increased risk for abacavir (ABC) hypersensitivity reaction (HSR). Screening was adopted in GlaxoSmithKline and ViiV Healthcare clinical trials in 2007 and human immunodeficiency virus treatment guidelines in 2008. Company meta-analyses of trials pre–HLA-B*5701 screening reported HSR rates of 4–8%. We analyzed the effectiveness of HLA-B*5701 screening on reducing HSR rates using clinical trial, Observational Pharmaco-Epidemiology Research & Analysis (OPERA) cohort, and spontaneous reporting data.

Methods

A meta-analysis examined 12 trials in 3063 HLA-B*5701–negative patients receiving an ABC-containing regimen from April 9, 2007, to September 22, 2015. Potential cases were identified using prespecified Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (drug hypersensitivity, hypersensitivity, anaphylactic reaction, anaphylaxis) and adjudicated against a Company ABC HSR case definition. Investigator-diagnosed cases were identified and rates were calculated. In the OPERA cohort, 9619 patients initiating their first ABC-containing regimen from January 1, 1999, to January 1, 2016, were identified. Patients were observed from regimen start until the earliest-following censoring event: ABC discontinuation, loss to follow-up, death, or study end (July 31, 2016). OPERA physicians evaluated events against OPERA definitions for definite/probable cases of ABC HSR; rates were calculated pre- and post-2008. The Company case definition was used to identify spontaneously reported cases for four marketed ABC-containing products; reporting rates were calculated using estimated exposure from sales data, through December 31, 2016.

Results

Suspected ABC HSR rates were 1.3% or less in the meta-analysis. In the OPERA cohort, the rate was 0.4% among patients initiating ABC post-2008 versus 1.3% pre-2008 (p<0.0001). Spontaneous reporting rates were low post-2008 (54 to 22 cases per 100,000 patient-years exposure [PYE]) versus pre-2008 (618 to 55 cases per 100,000 PYE).

Conclusions

Clinically suspected ABC HSR rates were 1.3% or less in HLA-B*5701–negative patients. Recognizing their limitations, data from the OPERA cohort and spontaneous reporting indicate that HLA-B*5701 screening has reduced reporting rates of suspected HSR in clinical practice. Where screening for HLA-B*5701 is standard care, patients should be confirmed negative for this allele before starting ABC treatment.

     

Control of sexually transmitted infections and prevention of HIV transmission: mending a fractured paradigm

Control of sexually transmitted infections (STIs) is feasible, leads to improved sexual and reproductive health and contributes to preventing HIV transmission. The most advanced HIV epidemics have developed under conditions of poor STI control, particularly where ulcerative STIs were prevalent. Several countries that have successfully controlled STIs have documented stabilization or reversal of their HIV epidemics.STI control is a public health outcome measured by reduced incidence and prevalence. The means to achieve this include: (i) targeting and outreach to populations at greatest risk; (ii) promoting and providing condoms and other means of prevention; (iii) effective clinical interventions; (iv) an enabling environment; and (v) reliable data.Clinical services include STI case management, screening and management of STIs in sex partners. Syndromic case management is effective for most symptomatic curable STIs and screening strategies exist to detect some asymptomatic infections. Presumptive epidemiologic treatment of sex partners and sex workers complement efforts to interrupt transmission and reduce prevalence. Clinical services alone are insufficient for control since many people with STIs do not attend clinics. Outreach and peer education have been effectively used to reach such populations.STI control requires effective interventions with core populations whose rates of partner change are high enough to sustain transmission. Effective, appropriate targeting is thus necessary and often sufficient to reduce prevalence in the general population. Such efforts are most effective when combined with structural interventions to ensure an enabling environment for prevention. Reliable surveillance and related data are critical for designing and evaluating interventions and for assessing control efforts.