Analysis of lesion localisation at colonoscopy: outcomes from a multi-centre U.K. study.

BACKGROUND: Colonoscopy is currently the gold standard for detection of colorectal lesions, but may be limited in anatomically localising lesions. This audit aimed to determine the accuracy of colonoscopy lesion localisation, any subsequent changes in surgical management and any potentially influencing factors. METHODS: Patients undergoing colonoscopy prior to elective curative surgery for colorectal lesion/s were included from 8 registered U.K. sites (2012-2014). Three sets of data were recorded: patient factors (age, sex, BMI, screener vs. symptomatic, previous abdominal surgery); colonoscopy factors (caecal intubation, scope guide used, colonoscopist accreditation) and imaging modality. Lesion localisation was standardised with intra-operative location taken as the gold standard. Changes to surgical management were recorded. RESULTS: 364 cases were included; majority of lesions were colonic, solitary, malignant and in symptomatic referrals. 82% patients had their lesion/s correctly located at colonoscopy. Pre-operative CT visualised lesion/s in only 73% of cases with a reduction in screening patients (64 vs. 77%; p = 0.008). 5.2% incorrectly located cases at colonoscopy underwent altered surgical management, including conversion to open. Univariate analysis found colonoscopy accreditation, scope guide use, incomplete colonoscopy and previous abdominal surgery significantly influenced lesion localisation. On multi-variate analysis, caecal intubation and scope guide use remained significant (HR 0.35, 0.20-0.60 95% CI and 0.47; 0.25-0.88, respectively). CONCLUSION: Lesion localisation at colonoscopy is incorrect in 18% of cases leading to potentially significant surgical management alterations. As part of accreditation, colonoscopists need lesion localisation training and awareness of when inaccuracies can occur.

Chemical-specific adjustment factors (inter-species toxicokinetics) to establish the ADI for steviol glycosides.

The acceptable daily intake (ADI) of commercially available steviol glycosides is currently 0-4 mg/kg body weight (bw)/day, based on application of a 100-fold uncertainty factor to a no-observed-adverse-effect-level value from a chronic rat study. Within the 100-fold uncertainty factor is a 10-fold uncertainty factor to account for inter-species differences in toxicokinetics (4-fold) and toxicodynamics (2.5-fold). Single dose pharmacokinetics of stevioside were studied in rats (40 and 1000 mg/kg bw) and in male human subjects (40 mg/kg bw) to generate a chemical-specific, inter-species toxicokinetic adjustment factor. Tmax values for steviol were at ∼8 and ∼20 h after administration in rats and humans, respectively. Peak concentrations of steviol were similar in rats and humans, while steviol glucuronide concentrations were significantly higher in humans. Glucuronidation in rats was not saturated over the dose range 40-1000 mg/kg bw. The AUC0-last for steviol was approximately 2.8-fold greater in humans compared to rats. Chemical-specific adjustment factors for extrapolating toxicokinetics from rat to human of 1 and 2.8 were established based on Cmax and AUC0-last data respectively. Because these factors are lower than the default value of 4.0, a higher ADI for steviol glycosides of between 6 and 16 mg/kg bw/d is justified.

A proposal for an upper limit of leucine safe intake in healthy adults.

Based on recent research, an upper limit of safe intake (ULSI) for leucine is proposed for healthy adults: 0.53 g/(kg·d). Because leucine has been used as a dietary supplement for many years in people practicing exercise and sport, further study with long-term exposure to leucine in this specific subpopulation should be performed to eventually adjust the ULSI.

The potential developmental neurotoxicity of calcium cyclamate in CD rats.

The developmental neurotoxicity of calcium cyclamate was evaluated in Sprague Dawley [Crl:CD(SD)] rats, administered in drinking water, in comparison to a concurrent control group (water) and a positive control group given propylthiouracil (PTU). Calcium cyclamate was administered to F0 females for 4 weeks prior to pairing, throughout mating, gestation and lactation and to F1 offspring from weaning to 12 weeks of age, PTU was administered by gavage to F0 females from Day 6 of gestation up to Day 20 of lactation. Target calcium cyclamate doses were 0, 250, 500 and 1,000 mg/kg bw/day, while the PTU dose was 0.5 mg/kg bw/day. No treatment-related effects of cyclamate were observed in either the F0 or F1 generations on reproductive performance or neurobehavioral development. In comparison, PTU exposure resulted in developmental delays, memory impairment and a number of neuropathological and morphometric outcomes. The results from the unique developmental neurotoxicity study design, corroborate the absence of hyperactivity and any other neurotoxic effects following cyclamate administration at levels up to 878 mg/kg bw/day in F0 females and 784 mg/kg bw/day in F1 animals. This demonstrates the suitability of PTU as a positive control and confirms the safe use of cyclamate as a no-calorie sweetener.

Sweet-taste receptors, low-energy sweeteners, glucose absorption and insulin release.

The present review explores the interactions between sweeteners and enteroendocrine cells, and consequences for glucose absorption and insulin release. A combination of in vitro, in situ, molecular biology and clinical studies has formed the basis of our knowledge about the taste receptor proteins in the glucose-sensing enteroendocrine cells and the secretion of incretins by these cells. Low-energy (intense) sweeteners have been used as tools to define the role of intestinal sweet-taste receptors in glucose absorption. Recent studies using animal and human cell lines and knockout mice have shown that low-energy sweeteners can stimulate intestinal enteroendocrine cells to release glucagon-like peptide-1 and glucose-dependent insulinotropic peptide. These studies have given rise to major speculations that the ingestion of food and beverages containing low-energy sweeteners may act via these intestinal mechanisms to increase obesity and the metabolic syndrome due to a loss of equilibrium between taste receptor activation, nutrient assimilation and appetite. However, data from numerous publications on the effects of low-energy sweeteners on appetite, insulin and glucose levels, food intake and body weight have shown that there is no consistent evidence that low-energy sweeteners increase appetite or subsequent food intake, cause insulin release or affect blood pressure in normal subjects. Thus, the data from extensive in vivo studies in human subjects show that low-energy sweeteners do not have any of the adverse effects predicted by in vitro, in situ or knockout studies in animals.

Using urinary solubility data to estimate the level of safety concern of low levels of melamine (MEL) and cyanuric acid (CYA) present simultaneously in infant formulas.

Melamine (MEL) and cyanuric acid (CYA) may occur simultaneously in milk products. There is no health based guidance value for the mixture of MEL+CYA. Limited toxicological data indicate that MEL+CYA toxicity occurs at levels lower than the toxic doses of the single compounds. The key adverse effect of MEL+CYA is the formation of crystals in the urinary tract, which is dependent on the solubility of the MEL+CYA complex. Urinary concentrations resulting from oral doses of MEL+CYA and MEL alone have been calculated from published data from animal studies. A human exposure scenario assuming consumption of infant formula contaminated at a level of 1 ppm of MEL and CYA each (2 ppm of MEL+CYA) was also analyzed. Margins of more than two orders or magnitude were observed between estimated urine concentrations known to be without detectable effects in rats and calculated human urine concentrations. Because the hazard is related to the physico-chemical characteristics of the mixture, there would be a negligible concern associated with crystal formation if the urinary concentration of the complex is within the solubility range. The solubility of MEL+CYA was higher in urine than in water. A strong pH-dependency was observed with the lowest solubility found at pH 5-5.5. The calculated human urinary concentration was about 30 times less than the solubility limit for MEL+CYA in adult human urine. Altogether, these data provide preliminary evidence suggesting that the presence of 1 ppm of MEL and CYA each in infant formula is unlikely to be of significant health concern.

The importance of tumor stage and relative survival analysis for the association between sex and survival after resection of colorectal cancer.

OBJECTIVE: The aim of this study was to determine whether the previously noted poorer survival of men after resection of colorectal cancer varied among clinicopathological tumor stages. SUMMARY BACKGROUND DATA: The question of whether sex is independently associated with prognosis after resection of colorectal cancer has been examined in numerous studies over the past 2 decades, but with conflicting results. METHODS: Data on 3,301 patients were drawn from a comprehensive, prospective hospital registry of all resections for colorectal cancer performed between January 1971 and December 2005. Statistical analysis employed Kaplan Meier estimation and relative survival analysis to adjust for differential male/female life expectancy in the general population. RESULTS: The relative survival of males was significantly less than that of females (P = 0.004) only in stage B. This was not accounted for by other negative pathology features and cause of death did not differ significantly between males and females. However, men with stage B tumor were more likely than women to experience postoperative morbidity, particularly a respiratory complication or a surgical complication requiring urgent reoperation. The sex difference in relative survival persisted among patients who had either a respiratory complication or an urgent reoperation (P = 0.003) but disappeared among those who had neither (P = 0.193). CONCLUSION: The poorer survival of men with stage B tumor was attributable to their greater postoperative morbidity which led to the earlier death of some due to causes unrelated to their colorectal cancer.

The 7th workshop on the assessment of adequate intake of dietary amino acids: summary of general discussion.

Extensive discussion sessions were held at the end of each of the 2 d of the workshop. Through the course of the workshop, it became clear that there were different opinions on how to use uncertainty factors to obtain upper levels of intake from no observed adverse effect levels of a particular nutrient and that the selection of an appropriate uncertainty factor would be rather arbitrary. Much of the discussion centered around the potential for using metabolic limits, expressed as the level of intake at which the major pathway of metabolism may approach saturation and at which the amino acid is metabolized by alternative pathways, as a measurable early or surrogate marker for amino acid excess and possible toxicity. After extensive discussion on various conditions that would need to be satisfied for metabolic limits to be used as markers of excessive intake of amino acids, there was a general consensus that methods such as measuring oxidation limits are an attractive approach that merit future investigation. It was noted that there are many data on the clinical use of glutamine, whereas data for proline are very scarce. There was recognition that regardless of the available data, there is regulatory pressure for setting upper levels of intake for amino acids and that much more data are required.

Biological fate of low-calorie sweeteners.

With continued efforts to find solutions to rising rates of obesity and diabetes, there is increased interest in the potential health benefits of the use of low- and no-calorie sweeteners (LNCSs). Concerns about safety often deter the use of LNCSs as a tool in helping control caloric intake, even though the safety of LNCS use has been affirmed by regulatory agencies worldwide. In many cases, an understanding of the biological fate of the different LNSCs can help health professionals to address safety concerns. The objectives of this review are to compare the similarities and differences in the chemistry, regulatory status, and biological fate (including absorption, distribution, metabolism, and excretion) of the commonly used LNCSs: acesulfame potassium, aspartame, saccharin, stevia leaf extract (steviol glycoside), and sucralose. Understanding the biological fate of the different LNCSs is helpful in evaluating whether reports of biological effects in animal studies or in humans are indicative of possible safety concerns. Illustrations of the usefulness of this information to address questions about LNCSs include discussion of systemic exposure to LNCSs, the use of sweetener combinations, and the potential for effects of LNCSs on the gut microflora.

Molecular approaches to the identification of biomarkers of exposure and effect--report of an expert meeting organized by COST Action B15. November 28, 2003.

In the past, the term biomarker has been used with several meanings when used in human and environmental toxicology as compared to pharmaceutical development. However, with the advent of molecular approaches and their application in the field of drug development and toxicology, the concept of biomarkers has to be newly defined. In the meeting, the experts found consent in defining the term and described the application of biomarkers in toxicology, drug development and clinical diagnostics. Molecular approaches to biomarker identification and selection lead to a large amount of data. Hence, the statistical analysis is challenging and special statistical problems have to be solved in biomarker characterization, of particular interest are attempts aiming at class discovery and prediction. Reliability and biological relevance are to be demonstrated for biomarkers of exposure and effect which is also true for biomarkers of susceptibility. It is envisaged that the application of biomarkers will expand from current use in pre-clinical toxicology to the risk characterization and risk assessment of chemicals and from early clinical phases of drug development to later phases and even into daily clinical use in diagnostics and disease classification.

Early experience of a virtual journal club.

BACKGROUND: Traditional journal club models based on didactic presentation sessions followed by group discussion have many limitations. To overcome some of these shortcomings, a virtual journal club (VJC) using social media and e-mail was developed. The aim of this study was to report the initial experience of this novel multimodal e-learning platform to facilitate journal club discussion and promote the development of critical appraisal skills. METHODS: Journal articles were discussed monthly via e-mail and social media. After a 3-week period of discussion, all comments were collated and group-generated critical appraisal summaries were fed back to participants. In addition, letters to the journal editors based on the group appraisal were submitted. A questionnaire survey to evaluate the VJC concept was also conducted. FINDINGS: After eight cycles of the VJC, the mean trainee participation rate was 29.6 per cent (range 21.1-42.1%). Senior trainees (≥4 years of postgraduate experience) were more likely to participate than more junior trainees (75.0 versus 21.1%; p = 0.005). The majority of participants thought that the VJC was educationally valuable, easy to participate in, helpful in keeping up to date with recent papers and useful in developing critical appraisal skills. Barriers to participation were lack of time, motivation and lack of experience in critical appraisal. In addition, the group-generated critical appraisal summaries derived from VJC discussions led to eight published 'letters to the editor'. Traditional journal club models based on didactic presentation sessions followed by group discussion have many limitations CONCLUSION: This novel VJC model is a feasible and popular method of delivering a journal club in the postgraduate setting.

Practical application of kinetic data in risk assessment--an IPCS initiative.

In this paper, guidance developed in a project of the International Programme on Chemical Safety (IPCS) initiative on Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals is considered in the context of its application in the assessment of the adequacy of physiological-toxicokinetic (PTK) modeling to inform quantitatively extrapolations for interspecies differences and human variability in dose-response assessment. This guidance was developed in the context of a framework, which permits the incorporation of quantitative chemical-specific data, relating to either toxicokinetics or toxicodynamics to replace part or all of the usual 100-fold default uncertainty factor for interspecies differences or human variability in the development of tolerable or reference doses or concentrations. However, since the guidance relates specifically to adequacy of kinetic or dynamic data to replace default for interspecies and human variability, it is also applicable to other approaches of dose-response analyses such as estimation of cancer potency or risk. The framework also supports probabilistic characterization, where data are sufficient. This guidance has been developed and refined through a series of planning and technical meetings and larger workshops, in which a broad range of participants from academia, government agencies, and the private sector have prepared and gained experience in application through case studies. The guidance for adequacy of kinetic data to replace default is presented in the context of several categories, including determination of the active chemical species, choice of the appropriate kinetic parameter and experimental data, the latter which includes reference to relevance of population, relevance of route, relevance of dose/concentration, and adequacy of number of subjects/samples. The principal objective of this guidance, which has been developed primarily as a resource for risk assessors, is to foster better understanding of the criteria for adequacy of chemical-specific data to quantitate interspecies differences and human variability in kinetics and dynamics, including PTK models. It is anticipated that the guidance will also encourage generation of appropriate data and models, and facilitate their incorporation in dose/concentration-response assessment for regulatory purposes. In this paper, the application of the guidance is considered primarily through reference to examples, with emphasis on those where PTK models have been informative.

Pesticide residue analysis and its relationship to hazard characterisation (ADI/ARfD) and intake estimations (NEDI/NESTI).

Over 800 pesticides are currently approved for use in one or more EU countries. The maximum residue levels (MRL) for agricultural pesticides are derived from field trials conducted under good agricultural practice (GAP). The MRL is a legally enforceable limit related to GAP. The results from field trials would only be used to establish MRLs if the estimated intake of residues did not exceed the acceptable daily intake (ADI) or acute reference dose (ARfD). However, the MRL is not linked to the ADI or ARfD, and could result in intakes considerably below the ADI/ARfD. This disconnection between hazard characterisation (ADI/ARfD) and potential exposure assessment (MRL) means that risk characterisation of pesticide residues is less transparent than for other chemicals present in human food. Residue levels at or below the MRL would not give intakes that exceed the ADI/ARfD but, despite this, there is public concern over such residues. Residue levels above the MRL have to be analysed on a case-by-case basis to determine if the intake could exceed the health-based limits. Other causes of public concern, such as the presence of multiple residues, are currently under investigation.

Botanical health products, positioning and requirements for effective and safe use.

Within the group of botanical products there is a large range of variation with regard to their properties. Some products are identical to foods while others come close to or are medicines. Botanical products are regulated differently within the different member states of the European Union (EU) and globally. They are regulated either as food or as medicinal products, and in the latter case often with simplified registration procedures. These differences are caused by differences in traditional use, in cultural and historical background, in scientific substantiation and in enforcement of current legislation. One may expect that in the future differences will remain, unless EU legislation is enacted with sufficient room for different approaches. The strengths and weaknesses of the different regulatory procedures have been reviewed and evaluated as well as the current methods for quality, efficacy and safety evaluation. Criteria to categorize botanical products have been defined, such that botanical products can be regulated under the current food and medicinal regulations. Furthermore, a decision tree has been developed as a tool to distinguish herbal medicinal products from botanical health products and vice versa, and to provide a stepwise framework for the assessment of safety and efficacy.

Salmonellosis as a differential diagnosis.

With a low incidence of Salmonella infection, salmonellosis is an uncommon problem in Scotland. It occurs in both immune-compromised and immune-competent patients. We present two cases of salmonellosis in immune-competent patients who had had a history of gastroenteritis. Diagnosis was delayed in one patient; however, both patients received appropriate treatment and made good recovery following their respective illnesses. Apart from acting as a reminder to consider salmonellosis as a differential diagnosis when managing patients with infective process, the cases also highlight the importance of concise history taking, and the importance of cultures-and-sensitivities in managing infectious cases.