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- Nordberg, Gunnar, et al.
(författare)
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Cadmium
- 2022. - 5
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Ingår i: Handbook on the toxicology of metals. - : Elsevier. - 9780128229460 ; , s. 141-196
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Bokkapitel (refereegranskat)abstract
- Cadmium (Cd) occurs with zinc and lead in sulfide ores. Elevated concentrations in air, water, and soil may occur close to nonferrous mining and metal refining industries. Cadmium metal has been used as an anticorrosive when electroplated onto steel. Cd compounds are used in batteries, as pigments and in solar panels. Between 10% and 50% of inhaled Cd will be absorbed and 5%-10% of ingested Cd. The accumulation of Cd in humans occurs in many tissues, with particularly long half-lives (10-30 years) in muscle, bone, kidney, and liver. Cd bound to metallothionein in plasma is filtered through the renal glomeruli and reabsorbed in the tubuli, where the metal ion is released and toxic effects occur. The average amount of Cd ingested in Japan and most European and North American countries is. <10-20. μg/day. The corresponding average urinary excretion of Cd is. <0.5-1.0. μg/day and the blood concentration is 0.2-0.7. μg/L in nonsmokers; it is twice as high in smokers. Acute inhalation of Cd in air, for example, from soldering or welding fumes, may lead to severe chemical pneumonitis. Long-term exposure to low air levels may lead to chronic obstructive lung disease and possibly to lung cancer. Long-term excessive exposure from the air or food leads to renal tubular dysfunction with low molecular weight proteinuria. It may also lead to disturbance of calcium metabolism, osteoporosis, and osteomalacia, mainly among postmenopausal women. A disease exhibiting these features. -called itai-itai disease. -occurred in the 1950s in a Cd-polluted area of Japan. Cd-induced cancer of the lungs, prostate, and other organs in animals and increased rates of cancer of the lungs and other organs in humans. The International Agency for Research on Cancer (IARC) classified Cd as a human carcinogen (Group 1). Adverse kidney effects occur in sensitive occupational groups, as well as in general population groups, after lifelong exposures giving rise to urinary Cd (UCd) of 2-4. μg/g creatinine. At such exposures, bone effects including osteoporosis and fractures may also occur in sensitive groups. Adverse bone and kidney effects may occur in a small but sensitive population group as a result of lifelong cadmium exposure with UCd of approximately 1. μg/g creatinine and higher, but the evidence is still inconclusive. This level of exposure occurs within general population groups in many countries. Osteomalacia is treated with large doses of vitamin D, but there is no effective treatment for other Cd-related effects. Because of the long half-life of Cd and the irreversibility of bone effects and some kidney effects, primary prevention is essential. The toxicological and environmental aspects of Cd have been reviewed in detail by Friberg et al. (1974, 1985, 1986), Tsuchiya (1978), Nriagu (1980, 1981), the WHO/IPCS (1992), the IARC (1993, 2012), Järup et al. (1998c), the Agency for Toxic Substances and Disease Registry (. ATSDR, 1999), Nordberg and Nordberg (2002), the European Union (. EU, 2003, 2007; ECHA 2020), Satarug and Moore (2004), and the World Health Organization Food and Agriculture Organization (. JECFA, 2004, 2012), the European Food Safety Authority (. EFSA, 2009, 2012), Akesson et al. (2014), the Scientific Committee on Occupational Exposure Limits (. SCOEL, 2017), and the International Union of Pure and Applied Chemistry (. Nordberg et al., 2018).
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| 2. |
- Turkmen, Sahruh, 1961-
(författare)
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Tolerance and antagonism to allopregnanolone effects in the rat CNS
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many studies have suggested a relationship between sex steroids and negative mental and mood changes in women. Allopregnanolone, a potent endogenous ligand of the GABA-A receptor and a metabolite of progesterone, is one of the most accused neuroactive steroids. Variations in the levels of neuroactive steroids that influence the activity of the GABA-A receptor cause a vulnerability to mental and emotional pathology. In women, there are physiological conditions in which allopregnanolone production increases acutely (e.g. stress) or chronically (e.g. menstrual cycle, pregnancy), thus exposing the GABA-A receptor to high allopregnanolone concentrations. In such conditions, tolerance to allopregnanolone probably develops. We have evaluated the 3β-hydroxy pregnane steroid UC1011 as a functional antagonist to allopregnanolone-induced negative effects in rats. In vivo, we used the Morris Water Maze (MWM) test of learning and, in vitro, we studied chloride ion uptake into cortical and hippocampal membrane preparations. The steroid UC1011 reduces the allopregnanolone-induced learning impairment in the MWM and the increase in chloride ion uptake induced by allopregnanolone. To detect whether chronic tolerance develops to an allopregnanolone-induced condition, male rats were pretreated with allopregnanolone injections for three or seven days. These rats were then tested in the Morris Water Maze for five days and compared with relevant controls. Rats with seven days’ allopregnanolone pretreatment experienced improved performance compared with the acutely allopregnanolone-exposed group, reflecting chronic tolerance development. To study the GABA-A receptor changes in acute allopregnanolone tolerance, we used the silent second (SS) anaesthesia threshold method. At acute tolerance, 90 minutes of anaesthesia, the abundance of the GABA-A receptor α4 subunit and the expression of the α4 subunit mRNA in the thalamus ventral-posteriomedial (VPM) nucleus were reduced. There was also a significant negative correlation between the increase in the allopregnanolone dose needed to maintain anaesthesia and the α4 mRNA in the VPM nucleus. We also investigated whether allopregnanolone tolerance was still present one or two days after the end of the anaesthesia-induced acute tolerance. Tolerance persisted to one day, but not two days, after the treatment and the α4 subunit mRNA expression in the VPM nucleus was negatively related to the allopregnanolone doses needed after one day. In conclusion, the current thesis shows that the substance UC1011 can reduce the allopregnanolone-induced negative effects in the water maze test. Chronic allopregnanolone tolerance can develop to the effects of allopregnanolone. Allopregnanolone tolerance persists one day after the induction of acute allopregnanolone tolerance. The GABA-A receptor α4 subunit in the thalamus might be involved in the development and persistence of acute tolerance to allopregnanolone.
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