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- Smits, KM, et al.
(författare)
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Association of metabolic gene polymorphisms with tobacco consumption in healthy controls
- 2004
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 110:2, s. 266-270
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphisms in genes that encode for metabolic enzymes have been associated with variations in enzyme activity between individuals. Such variations could be associated with differences in individual exposure to carcinogens that are metabolized by these genes. In this study, we examine the association between polymorphisms in several metabolic genes and the consumption of tobacco in a large sample of healthy individuals. The database of the International Collaborative Study on Genetic Susceptibility to Environmental Carcinogens was used. All the individuals who were controls from the case-control studies included in the data set with information on smoking habits and on genetic polymorphisms were selected (n = 20,938). Sufficient information was available on the following genes that are involved in the metabolism of tobacco smoke constituents: CYPIAI, GSTMI, GSTTI, NAT2 and GSTPI. None of the tested genes was clearly associated with smoking behavior. Information on smoking dose, available for a subset of subjects, showed no effect of metabolic gene polymorphisms on the amount of smoking. No association between polymorphisms in the genes studied and tobacco consumption was observed; therefore, no effect of these genes on smoking behavior should be expected.
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- Kristensen, T N, et al.
(författare)
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The increase of fluctuating asymmetry in a monoclonal strain of collembolans after chemical exposure - discussing a new method for estimating the environmental variance
- 2004
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1872-7034 .- 1470-160X. ; 4:1, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- The increasing demand for detecting and quantifying the negative effects on natural habitats caused by anthropogenic activity has led to the development of impact assessment tools. Here, we propose a monitoring method based on the concept of developmental instability (DI) estimated from fluctuating asymmetry (FA) in bilateral morphological traits in a monoclonal strain. The use of monoclonal populations conveys certain advantages over sexual populations when interpreting fluctuating asymmetry results. This is because the inherent problems of genetic heterogeneity are circumvented. Our investigation demonstrates in practice, how an estimate of the environmental component of the phenotypic variance in a population can be achieved. This estimate can be used to eliminate samples where the presence of macro environmental variance has influenced the estimated level of fluctuating asymmetry significantly. Avoiding the confounding effect due to the presence of genetic variance and controlling the environmental variance component enable a more accurate estimate of the possible detrimental effects of the putative stressing agents. We used a clonal strain of the springtail Folsomia candida exposed to three different contaminants; tributyltin, nonylphenol and bis(2-ethylhexyl)-phthalate (DEPH), in order to test the general applicability of the proposed method. The results show that the method is efficient in discriminating between environments exposed to chemical stress and control environments. However, establishing an actual dose-response relationship was only possible for one of the contaminants, nonylphenol.
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- Lundkvist, B, et al.
(författare)
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Cerebrospinal fluid hydrodynamics after placement of a shunt with an antisiphon device : a long-term study.
- 2001
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Ingår i: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 94:5, s. 750-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT: Few studies have been performed to investigate the cerebrospinal fluid (CSF) hydrodynamic profile in patients with idiopathic adult hydrocephalus syndrome (IAHS) before and after shunt implantation. The authors compared the in vivo CSF hydrodynamic properties, including the degree of gravity-induced CSF flow, of a shunt with an antisiphon device with a standard shunt.METHODS: Twelve patients with IAHS underwent insertion of shunts with Delta valves. Clinical testing, magnetic resonance imaging, and CSF hydrodynamic investigations were conducted with intracranial pressure (ICP), gravity effect, and pressure-flow curve of the shunt estimated at baseline and at 3 and 12 months postoperatively. No shunt was revised. Despite postoperative clinical improvement in all patients who received Delta valves, the mean ICP was only moderately reduced (mean decrease at 3 months 0.3 kPa [p = 0.02], at 12 months 0.2 kPa [not significant]). Patients with the greatest increase in ICP preoperatively had the most pronounced decrease postoperatively. The hydrostatic effect of the Delta valves was significantly lower than with the Hakim shunts (0.1-0.2 kPa compared with 0.6 kPa). The increased conductance (that is, lowered resistance) was up to 14 times higher with the Delta valves compared with preoperative levels.CONCLUSIONS: The function of a CSF shunt may be more complicated than previously thought; the subcutaneous pressure acting on the antisiphon device can modify the shunt characteristics. A compensatory increase in CSF production may counteract the increased outflow through the shunt. The improved CSF outflow conductance may increase the intracranial compliance and thereby dampen a pathological ICP waveform.
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