The present research was conducted to evaluate the effect of mitogen pre-exposure on CCl4-induced hepatotoxicity. Male Wistar rats were administered a single i.p. injection of CCl4 (0.3 ml kg-1 in ...corn oil) 48 h following either a single dose of lead nitrate (0.33 mg kg-1) or distilled water via i.v. injection. Hepatotoxicity, as measured by serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, was monitored 6, 24, 48, 72 and 120 h after CCl4 exposure. The lead nitrate-pretreated rats displayed markedly lower serum ALT and AST levels at 24, 48 and 72 h than rats pretreated with distilled water. However, treatment with the antimitotic agent colchicine did not alter the lead-induced protection. These findings suggest that the lead-induced protection is not associated with the major mitogenic response of lead, despite its strong temporal association. A critical review of the available toxicological data also argues against the lead protection being a function of its capacity to inhibit cytochrome P-450.
This paper reviewed the biomedical and toxicological database concerning the use of mink as a predictive model of human responses. It is concluded that substantial information exists on the mink ...genetics, physiology, metabolism, nutritional requirements, and susceptibility to infectious disease; and provides a foundation upon which interspecies extrapolation may be considered. In addition, information on the response of mink to several dozen toxic substances revealed that mink respond in a qualitatively and quantitatively similar manner to other more commonly employed species as well as humans. Our conclusion does not infer that mink should be used routinely in toxicological testing for estimation of human responses. However, it indicates that toxicological data from this species may be a useful complement in risk assessment processes based upon data obtained from traditionally employed models such as rats and dogs.
Background Comprehensive data are unavailable for cardiac abnormalities in patients with neurofibromatosis type 1 (NF1). The goal of this study was to evaluate the prevalence of cardiovascular ...abnormalities with echocardiography with color Doppler scan (ECHO) in a large, consecutive series of patients with NF1. Methods We studied 48 patients with NF1 (mean age, 10 years). Thirty healthy subjects comparable for age and sex served as the control group. All ECHO studies were performed by the same cardiologist and reviewed by a second cardiologist blinded to the physical findings of the subjects. Results Cardiac abnormalities were found in 13 of the 48 young patients (27%). A secundum atrial septal defect with a left to right shunt was found in 2 children. ECHO evidence of mild left pulmonary artery stenosis was found in 1 participant. A moderate coarctation of the thoracic aorta was found in 1 patient. ECHO criteria for mitral valve prolapse and evidence of trivial mitral regurgitation with myxomatous mitral valve was present in 1 case. Mild mitral regurgitation was found in 2 patients. A regurgitant mild flow signal was detected from the aortic valve in 2 subjects. Atrial septal aneurysm was found in 2 patients without patent foramen ovale. Two patients had septal to posterior left ventricular free wall ratio greater than 1.5, suggesting hypertrophic cardiomyopathy. Conclusion This is the first attempt to evaluate the prevalence of cardiovascular abnormalities in patients with NF1 with ECHO. The study's most striking finding is the high prevalence of cardiovascular abnormalities. Congenital lesions have potential long-term hemodynamic consequences that justify an early diagnosis. Thus, a cardiologic assessment at regular intervals, including ECHO study, is mandatory for patients with NF1. (Am Heart J 2002;143:883-8.)
STEM Language can be the Stem of the Problem Rugh, Michael. S.; Calabrese, Julia E.; Madson, Mykala A. ...
2018 IEEE Frontiers in Education Conference (FIE),
2018-Oct.
Conference Proceeding
Engineering collaboration requires successful interdisciplinary communication between professionals who have highly specialized, content specific vocabularies. STEM language research has shown that ...people encounter barriers to communication due to different understandings of particular words. Additionally, linguistics research has shown that confusion over specific words can be due to many causes such as alternate meanings or senses associated with that word. However, very little research has studied interdisciplinary task collaboration within a linguistics-based framework. This study identified and categorized patterns of words and phrases that caused confusion during an engineering task at a STEM summer camp for secondary teachers. The results demonstrated that confusion over meanings of words inhibited the participants' progress toward completing the task. When two participants had a common or shared vocabulary, they were able to negotiate meaning, resulting in greater success on the task.
There is much debate over the fundamental shape of the dose-response curve in the low-dose zone, particularly in the fields of toxicology and risk assessment. The defaults, principally accepted ...dose-response models in the major texts in these areas and in government regulatory activities, are a threshold model for non-carcinogens and a linear model for most carcinogens. We have argued that in properly designed studies the U-shaped hormetic response predominates and is more fundamental. In this article, a broad range of basic issues associated with the acceptance of U-shaped dose responses as central to toxicology, pharmacology and their applications to risk assessment and medicine will be discussed.
The capacity of animal models to predict the responses of humans to carcinogenic agents in light of the occurrence of human heterogeneity is assessed in this paper. It is widely accepted that human ...susceptibility to toxic substances, including carcinogens, is highly variable. At the same time, it is believed that the conventional rodent models, which are usually highly inbred and reared in standard ways, display a very homogeneous response to toxic agents, including carcinogens. The question then becomes, To which narrow band of the broad spectrum of human responses can specific animal models likely be extrapolated? First, the occurrence of human heterogeneity is examined with respect to a broad range of biological characteristics (e.g., aryl hydrocarbon hydroxylase activity, epoxide hydrase activity, glutathione S-transferase activity, beta-glucuronidase activity, debrisoquine hydroxylation, and DNA adduct formation), with particular emphasis on those which affect responses to carcinogens. Second, the occurrence of heterogeneity for selected animal models for these characteristics is assessed and the outcomes are related to the spectrum of human responses noted above.
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