Estimation of Benchmark Rice Cadmium Doses as Threshold Values for Abnormal Urinary Findings with Adjustment for Consumption of Jinzu River Water

We performed this study to determine whether both eating cadmium (Cd)-polluted rice and drinking and/or cooking with Jinzu River water are associated with renal tubular dysfunction. A multiple logistic regression analysis of retrospective data indicated that both factors may contribute to this condition. Estimated threshold values of rice Cd concentration in men were 0.13–0.27 ppm and 0.09–0.18 ppm in women, without adjustment for use of Jinzu River water. The additional influence of drinking and/or cooking with Jinzu River water was estimated to be about 0.008 ppm.     

Refining the threshold of toxicological concern (TTC) for risk prioritization of trace chemicals in food

Due to ever-improving analytical capabilities, very low levels of unexpected chemicals can now be detected in foods. Although these may be toxicologically insignificant, such incidents often garner significant attention. The threshold of toxicological concern (TTC) methodology provides a scientifically defensible, transparent approach for putting low-level exposures in the context of potential risk, as a tool to facilitate prioritization of responses, including potential mitigation. The TTC method supports the establishment of tiered, health-protective exposure limits for chemicals lacking a full toxicity database, based on evaluation of the known toxicity of chemicals which share similar structural characteristics. The approach supports the view that prudent actions towards public health protection are based on evaluation of safety as opposed to detection chemistry. This paper builds on the existing TTC literature and recommends refinements that address two key areas. The first describes the inclusion of genotoxicity data as a way to refine the TTC limit for chemicals that have structural alerts for genotoxicity. The second area addresses duration of exposure. Whereas the existing TTC exposure limits assume a lifetime of exposure, human exposure to unintended chemicals in food is often only for a limited time. Recommendations are made to refine the approach for less-than-lifetime exposures.     

A finite element model of the electrically stimulated human thigh: changes due to denervation and training

Abstract:  The complete denervation of muscles leads to changes in the muscle fibers as well as in the surrounding tissue. Concerning excitability the most important changes are reductions in fiber diameter, in muscle cross-sectional area, and in electrical conductivity of the muscle tissue. These changes can be partially reversed by intensive electrical stimulation.
Evaluation of a 3D finite element axial symmetric model of the human thigh shows that the training leads to a reduction in threshold values between 17 and 51 percent, depending on the position of the fiber in the thigh. Single parameter variation clarifies the influence of each of the different factors. The electrode position was found to be most effective with the electrodes as far apart from each other as possible. Due to (i) comparatively higher changes in potentials at the distal electrode; and (ii) variations in sodium channel dynamics, lowest threshold values can be reached with a hyperpolarizing first phase of the biphasic impulse at the distal electrode. The tissue of the denervated muscle is known to be highly inhomogeneous. Simulations demonstrate that the related irregularities in the field can actually initiate fiber activation.
3D finite element simulations show the overall positive effects of FES on muscle tissue, especially an improved excitability of the muscle fibers. Furthermore the method gives an insight into the relations between potential distribution, electrode position, geometric effects, and muscle fiber activation that cannot be obtained by measurements.     

A Ketogenic Diet Increases the Resistance to Pentylenetetrazole-Induced Seizures in the Rat

Summary: Purpose: The purpose of this study was to test the hypothesis that a ketogenic diet would increase the resistance of rats to pentylenetetrazole (PTZ)-induced seizures and to understand the relation of ketonemia to seizure resistance.
Methods: A freely consumed, high-fat (ketogenic) diet was administered to male Sprague-Dawley rats for 5–10 weeks, while control animals were fed either rodent chow or a high-carbohydrate diet. Ketonemia was measured as plasma levels of β-hydroxybutyric acid (β-OHB). Seizures were induced by tail-vein infusion of pentylenetetrazole.
Results: The ketogenic diet produced a highly significant (p <0.01) increase in β-OHB levels within 5 days. Induction of seizures by PTZ 35 days after animals were placed on their respective diets showed that ketogenic animals had a significantly (p <0.01) increased threshold for seizure induction compared with those fed an isocaloric diet of either high-carbohydrate or normal rodent chow. Ketogenic animals did not exhibit increased seizure severity relative to controls, despite receiving consistently higher doses of PTZ.
Conclusions: The ketogenic diet resulted in an increased seizure threshold, confirming the hypothesis, and seizure threshold was found to be a direct function of the level of ketonemia.     

Self-reported pain sensitivity: lack of correlation with pain threshold and tolerance.

Many recent studies and several reviews have highlighted the potential clinical applications of experimental pain testing (e.g., for predicting post-surgical pain, treatment responsiveness, etc.). However, the implementation of quantitative sensory testing of pain sensitivity on a broad scale is limited by requirements of time, equipment, and expertise, and their associated costs. One reasonable question is whether one can obtain, via self-report, a valid index of an individual's pain sensitivity and pain tolerance. We analyzed data from a large number of subjects (n=505) who had undergone standardized thermal pain testing, and found that while higher self-reported pain sensitivity was associated with higher scores on a measure of anxiety, no relationship was observed between subjects' self-report of pain sensitivity and subjects' actual pain threshold or tolerance. These findings suggest that circumventing psychophysical pain testing by assessing individuals' self-reported pain sensitivity is unlikely to be a useful strategy.     

Deciding to resuscitate extremely premature babies: How do parents and neonatologists engage in the decision?

Parents at risk of delivering a baby at the threshold of viability are faced with a critical decision. When a child is born between 23 and 25 weeks of gestation, parents are asked to decide whether or not to resuscitate their child. In essence, they are faced with a choice between life and death. We conducted a qualitative study to explore how parents and neonatologists engage in decision-making in a context of imminent and unplanned delivery at the threshold of viability. Twelve parents and attending neonatologists in a specialized tertiary care centre in Montreal, Canada were separately interviewed immediately following neonatal consultation. Results highlight how neonatologists and parents engage in decision making from different standpoints: while neonatologists focus on the management of the unborn baby, parents have yet to fully conceptualize their infant as a distinct entity since they are in a process of grieving their pregnancy and their parenthood project. Moreover, in their attempt to ensure an informed decision, neonatologists adopt either of two models through provision of the most up-to-date and objective information available: "remaining as neutral as possible to allow parents to make their own decision", or, "formulating a proposal to which parents can choose or not to assent". Overall, if the provided information fits parents' expectations, they tend to feel confident with their decision. However, if it does not take their experience into account, their decision is experienced as a solitary process. Parents express the need to receive more than just factual information from neonatologists. They also require support and engagement from caregivers to manage the uncertainty. This brings into question the traditional concept of neutral informed consent and suggests the necessity of a shared decision-making model to ensure that the decision to resuscitate extremely premature babies, at the limits of viability, becomes a truly ethical task.     

Thick activation detectors for neutron spectrometry using different unfolding methods: sensitivity analysis and dose calculation

This paper discusses the use of threshold detectors of extended sizes for low intensity neutron fields' characterization.The detectors were tested by the measurement of the neutron spectrum of an ²⁴¹Am-Be source. Integral quantities characterizing the neutron field, required for radiological protection, have been derived by unfolding the measured data. A good agreement is achieved between the obtained results and those deduced using Bonner spheres. In addition, a sensitivity analysis of the results to the deconvolution procedure is given.     

早产儿视网膜病变阈值病变的相关因素分析

目的 对早产儿视网膜病变(ROP)不同转归一自然退行与阈值病变各相关因素进行分析,以探讨与ROP阈值病变有关的因素.方法 回顾性分析2008年5月至2009年7月在吉林大学第一医院新生儿科收治的83例确诊ROP的早产儿相关临床数据,并进行统计学分析.结果 在83例不同程度ROP患儿中(166只眼),自然退行51例(102只眼,占ROP患儿61.45％),阈值病变32例(64只眼,占ROP患儿38.55％).使用t检验和logistic回归分析,结果表明ROP阈值病变组的胎龄较ROP自然退行组小,产次较ROP自然退行组次数多,差异均有统计学意义(P＜0.05);排除其他因素干扰后,男性、机械呼吸及发生败血症与ROP阈值病变有关,组间差异均有统计学意义(P＜0.05).结论 小胎龄、多产次,男性、使用机械呼吸、发生败血症与ROP不能自然退行有关.