D and C Red No. 9: genotoxic or non-genotoxic carcinogen?

The azo-compound, D and C Red No. 9 was assayed for genotoxicity in vivo using the rat micronucleus test and the rat ex vivo liver UDS assay. Uniformly negative results were obtained in both assays, even though large oral doses were used (2 g/kg). These results suggest that the tumorigenic effects of this compound in rats are mediated through non-genotoxic rather than a genotoxic mechanism. Further experiments using additional end-points such as 32P-post-labelling would further substantiate this conclusion.     

Salmon Bias or Red Herring?

The purpose of this research is to empirically test the salmon bias hypothesis, which states that the “healthy migrant” effect—referring to a situation in which migrants enjoy lower mortality risks than natives—is caused by selective return-migration of the weak, sick, and elderly. Using a unique longitudinal micro-level database—the Historical Sample of the Netherlands—we tracked the life courses of internal migrants after they had left the city of Rotterdam, which allowed us to compare mortality risks of stayers, returnees, and movers using survival analysis for the study group as a whole, and also for men and women separately. Although migrants who stayed in the receiving society had significantly higher mortality risks than natives, no significant difference was found for migrants who returned to their municipality of birth (returnees). By contrast, migrants who left for another destination (movers) had much lower mortality risks than natives. Natives who left Rotterdam also had significantly lower mortality risks than natives who stayed in Rotterdam. Female migrants, in particular, who stayed in the receiving urban society paid a long-term health price. In the case of Rotterdam, the salmon bias hypothesis can be rejected because the lower mortality effect among migrants was not caused by selective return-migration. The healthy migrant effect is real and due to a positive selection effect: Healthier people are more likely to migrate.     

C. difficile ribotype 027 or 176?

Clostridium difficile is a major nosocomial pathogen of present times. The analysis of 624 C. difficile strains from 11 hospitals in the Czech Republic in 2013 revealed that 40 % of isolates belonged to ribotype 176. These results suggest that the incidence of CDI (C. difficile infection) in the Czech Republic has increased probably in connection with C. difficile ribotype 176. The molecular systems Xpert C. difficile Epi assay (Cepheid Inc., Sunnyvale, CA) diagnoses toxigenic strains and supports C. difficile ribotype 027 determination based on three specific target places in the toxigenic C. difficile genome. Twenty-nine strains cultivated from stool specimens were evaluated by the Xpert systems as presumed C. difficile PCR ribotype 027 were confirmed as a C. difficile ribotype 176 based on ribotyping. A further 120 C. difficile strains of ribotype 176 were examined for the presence of genes tcdB, cdtB and deletion in position 117 in the tcdC gene. Our experience shows that due to the correspondence of the target places, C. difficile ribotype 176 may be interpreted as ribotype 027 by Xpert C. difficile Epi assay (Cepheid Inc., Sunnyvale, CA). Further molecular analysis as ribotyping based on capillary electrophoresis is needed to differentiate between C. difficile ribotypes 027 and 176 for appropriate epidemiological situation control on local and national levels.     

International Commission for Protection Against Environmental Mutagens and Carcinogens. ICPEMC publication No. 17. Can a mechanistic rationale be provided for non-genotoxic carcinogens identified in rodent bioassays?

In a recent survey of the results of the National Cancer Institute/National Toxicology Program's Carcinogenesis Bioassay Program, Ashby and Tennant (1988) drew attention to the high proportion of carcinogens that were non-genotoxic insofar as their response to the Salmonella-microsome test was concerned. The present review contrasts these findings with what is known mechanistically about non-genotoxic carcinogens that affect the tissues which are considered to be particularly prone to non-genotoxic tumor induction. Excessive and often thresholded increases in cellular proliferation in the affected tissues appear to be one common feature in tumor induction by these agents, which act either through cytotoxicity followed by regeneration or through hormone-mimetic action. It is suggested that a weight of the evidence approach on a chemical by chemical basis is necessary to decide the relevance of these agents to the human situation.     

6 or 9?

In this article the author offers an original interpretation of patterns found on the world's most ancient felts (Fifth Century BCE). These artifacts have been recovered from frozen burial mounds in the Altai Mountains. The interpretation presented here constitutes a new approach to the study of ornamentation as a system of symbols.     

Reply To-Healy D. and Waterhouse J.M.: the Circadian System and Affective Disorders: Clocks or Rhythms? Chronobiologic Disorders, Social Cues and the Light-Dark Cycle

In their monograph (1), Healy and Waterhouse quite thoughtfully distinguish between the altered shapes of circadian rhythms and their entrainment (synchronization). Although there is a great deal of evidence that various influences can alter the shape of circadian rhythms (“masking”), the literature on multiple time cues (zeitgebers) entraining different pacemakers is less convincing. In humans, evidence for nonphotic (social and activity-rest cycle) zeitgebers is restricted to human studies of anchor sleep (2), to data from Wever (3) and Czeisler (4) and to animal studies by Mrosovksy (5) and Turek (6). Until proven otherwise, it seems most likely that social cues primarily affect the sleep-wake cycle (activity-rest cycle), which- being loosely coupled to the endogenous circadian pacemaker-can be dissociated from it and the overt rhythms that are driven by it.     

F.G. syndrome: a rare and/or extremely polymorphic syndrome?

We report a case of mental retardation associated with multiple congenital anomalies suggesting an F.G. syndrome. We discuss problems concerning genetic counselling and the management of future pregnancies. Unfortunately, no concrete strategy, concerning prenatal diagnosis, can be proposed.     

Overexpression and refolding of human Cyclin D3. A reliable method or not?

Cyclin D3 is a regulatory protein associated in a variety of human tumors. Despite several studies involving Cyclin D1 and D2, there are few articles that investigate the role of Cyclin D3. Therefore, this study aimed to produce and characterize Cyclin D3 using the Escherichia coli expression system and a protein refolding protocol. The anionic detergent SDS was used to solubilize the protein, then the solution were kept at 4 °C to precipitate SDS. After removing the precipitate by centrifugation, the supernatant was applied to the Ni-NTA column to purify His- tagged Cyclin D3. The recombinant protein shown to be refolded in a denaturation study by fluorescence spectroscopy at increasing concentrations of guanidine hydrochloride. The protein secondary structure, evaluated by circular dichroism, is composed of 39 % α helix and 15 % β-strands. In addition, the study aimed to validate the refolding protocol used to obtain Cyclin D3 from E. coli inclusion bodies.     

Red snapper management in the Gulf of Mexico: science- or faith-based?

The most controversial fishery in U.S. waters of the Gulf of Mexico (Gulf) is for northern red snapper Lutjanus campechanus, which collapsed in the late 1980s when stock biomass became too low to be fished commercially in the eastern Gulf. Red snapper management began in 1989; the stock is now showing signs of recovery. The Gulf of Mexico Fishery Management Council has been slow to sufficiently reduce catches of the directed fisheries to rebuild the stock in a timely fashion, although compliance with the Magnuson-Stevens Reauthorization Act of 2006 (MSRA) required substantial cuts in the harvest of red snapper beginning in 2007. In our opinion, this could have been avoided if conservative management practices had been adopted earlier. We believe that ‘faith-based fisheries’ arguments have been used to defer effective management of red snapper in the Gulf, which in turn has strained the relationship between science, management, and stakeholders there. We provide a simple empirical argument and alternate interpretations of a recently published perspective on the historical fishery of red snapper in the Gulf to conclude that the preponderance of evidence used in the agency stock assessment process, and the simple arguments made here, do not support the perspective that the red snapper stock has increased in size sufficiently to defer compliance with the MSRA.     

A. A. Ukhtomskiĭ and I. P. Pavlov: a controversy or a dialogue?

Pavlov's concept of conditioned reflexes and Ukhtomskii theory of dominanta fall within the biological line in physiology. They unravel the integral adaptive and active nature of the organism behavior in the environment. It is impossible to develop modern concepts about the determinants of goal-directed behavior of animals and voluntary activity of humans without in-depth study of the achievements of these Russian physiological schools which not only formed the methodological basis for the current studies but also directed the way for their further development.     

Red leaves, insects and coevolution: a red herring?

W.D. (Bill) Hamilton proposed that coevolution between plants and herbivorous insects explains the bright autumnal colouration of leaves. Accordingly, plants invest in bright signals to reduce their herbivore load, whereas insects use these bright signals to identify less-defended hosts more efficiently. Archetti and Brown have recently revisited this theory by explaining its basic predictions and providing new research perspectives. Their work presents an important basis to our understanding of non-green leaf colouration, provided that alternative adaptive explanations on the photoprotective and antioxidant role of leaf pigments, or their possible function in crypsis to herbivores are incorporated into future research.