Temporal and spatial changes in mercury concentrations in the North Atlantic as indicated by museum specimens of glacier lanternfish Benthosema glaciale (Pisces: Myctophidae)

Museum specimens of glacier lanternfish Benthosema glaciale were used to investigate long-term variations in mercury concentration of mesopelagic organisms from the North Atlantic. B. glaciale is an abundant mesopelagic fish species in the boreal and sub-polar pelagic regions of the North Atlantic, playing an important role in the cycling of energy in the oceanic food webs of these systems. We used 35 museum specimens of lanternfish, collected from the Gulf Stream biogeographic region between 1936 and 1993, to test for long-term variations in mercury concentrations. In addition, we studied the mercury concentrations throughout the geographical range of the species, using 105 specimens collected around 1970s. Mercury concentrations were similar over time; however there was evidence of a noteworthy increase in mercury contamination during the World War II (1941) followed by a general decrease with lowest concentrations being found in 1954 and 1993. Significant differences were found between the different studied areas, probably reflecting different degrees of anthropogenic contamination. The results presented here indicate that museum myctophids may be suitable for the assessment of historical changes in mercury contamination of marine ecosystems.     

Hair mercury concentrations and in vitro fertilization (IVF) outcomes among women from a fertility clinic

Total hair mercury (Hg) was measured among 205 women undergoing in vitro fertilization (IVF) treatment and the association with prospectively collected IVF outcomes (229 IVF cycles) was evaluated. Hair Hg levels (median = 0.62 ppm, range: 0.03–5.66 ppm) correlated with fish intake (r = 0.59), and exceeded the recommended EPA reference of 1 ppm in 33% of women. Generalized linear mixed models with random intercepts accounting for within-woman correlations across treatment cycles were used to evaluate the association of hair Hg with IVF outcomes adjusted for age, body mass index, race, smoking status, infertility diagnosis, and protocol type. Hair Hg levels were not related to ovarian stimulation outcomes (peak estradiol levels, total and mature oocyte yields) or to fertilization rate, embryo quality, clinical pregnancy rate or live birth rate.     

Hepatic and renal metallothionein induction by an oral equimolar dose of zinc, cadmium or mercury in mice.

The hepatic and the renal subcellular distribution of zinc, cadmium or mercury and induction of tissue metallothionein (MT) at 24, 48 and 72 h following an oral equimolar dose (15 micro;mol metal/kg) of zinc (II) chloride, cadmium (II) chloride or mercury (II) chloride in male albino mice were investigated. There was a moderate increase in hepatic and renal zinc levels mainly in their nuclear mitochondrial fraction (NMF) 24 h post zinc chloride administration. Subsequently, the hepatic zinc increased and the renal zinc declined with time. The zinc-induced hepatic MT level was maximum at 48 h, which decreased slightly thereafter, while there was no marked increase in renal MT level at any time interval. The cadmium was equally distributed in liver and kidney more in their supernatant cytosol fraction (SCF) than in their NMF at 24 h after a dose of cadmium chloride. The cadmium levels showed a decreasing trend in hepatic fractions and an increasing trend in renal fractions with time. The cadmium-induced hepatic and renal MT were substantial at 24 h post cadmium administration, the former decreased thereafter while the latter enhanced at 48 h before declining. The accumulation of mercury in kidney was 1.5 times that in liver, which was localised more in their SCF than in their NMF at 24 h in response to a dose of mercuric chloride. The mercury levels of hepatic and renal subcellular fractions started declining after 24 h and at 72 h they were significantly lower. The induction of hepatic and renal MT was maximum at 24 h after mercuric chloride administration, which declined thereafter concomitant with the decrease in their mercury levels. However, the MT levels in both the organs remained considerably higher than in normal animals at 72 h post exposure. The results show that the accumulation of metal in liver and kidney follows the order: Hg > Cd > Zn and the induction of MT follows Hg > Cd > Zn in liver and Cd > Hg > Zn in kidney. The alterations in zinc and copper homeostasis were more marked in liver than in kidney and follows the order: Hg > Cd > Zn.     

Gonad histology and vitellogenin concentrations in brown trout (Salmo trutta) from Danish streams impacted by sewage effluent

Brown trout (Salmo trutta) collected from a number of Danish streams impacted by sewage effluent were examined for alterations to gonadal development and induction of vitellogenin synthesis. Among fish collected in June/July 2000/2001 and November 2002 higher levels of plasma vitellogenin were found in males from six streams impacted by sewage effluent compared to males from their respective reference sites. A direct non-competitive ELISA was developed for brown trout vitellogenin in order to perform the vitellogenin measurements. Intersex in females with no apparent relation to sewage effluent exposure was observed at all sites. In one stream, male brown trout with a very high level of vitellogenin were concomitantly found to have a high degree of vacuolation of the testes and a presence of only the early spermatogenic stage, spermatogonia. The cause of these alterations to the testis structure is unclear. However, as a high level of plasma vitellogenin in these males indicated estrogenic exposure, the vacuolation might also be a result of endocrine disruption causing delayed or disrupted spermatogenesis.     

Comparative assessment of blood mercury in American alligators (Alligator mississippiensis) from Coastal North Carolina and Florida

Ecotoxicology - Mercury (Hg) is a widespread and harmful persistent pollutant of aquatic ecosystems. Except for the northern most populations of American alligators (Alligator Mississippiensis)...     

Comparison of cytopathological changes induced by mercury chloride exposure in renal cell lines (VERO and BGM)

The response to mercury chloride was assessed in two cell lines of renal origin, determining the range of toxic concentrations by Neutral Red assay after 24-h of exposure. Morphological changes in the Buffalo Green Monkey (BGM) and VERO cell lines after exposure to subcytotoxic doses (0.045 and 0.038 mM, respectively) equivalent to EC10 (effective concentrations 10%) of mercury chloride were evaluated at the structural and ultrastructural level by optic, transmission and scanning microscopy. Using transmission electron microscopy, the most notable findings in treated cells were the presence of intracytoplasmic inclusion bodies and apoptotic bodies. Scanning microscopy pointed to a cell with a disrupted perinuclear region and a decreased number of surface microvilli. Similar alterations in both in vivo and in vitro experiments have been described by other authors. We conclude that BGM and VERO renal cell lines can be considered as useful tools for toxicological studies involving mercury chloride.     

Scorpion envenoming in the North of Mali (West Africa): Epidemiological, clinical and therapeutic aspects

Scorpion envenomation remains a poorly known problem in sub-Saharan Africa, particularly in Mali, where the incidence is high in Northern area of the country (Sahara desert). We conducted a prospective study in two district health centers, Kidal and Tessalit (North-east of Mali), to describe the epidemiological, clinical and therapeutic features of scorpion stings. This study consisted of an exhaustive follow-up from admission to discharge of all patients stung by scorpions. Of a total of 282 cases recorded during one year, 207 (73.4%) occurred in Kidal, and the remaining 75 (26.6%) took place in Tessalit. The annual incidence was significantly higher in Tessalit (437 cases/100 000 population/year) than in Kidal (243 cases/100,000 population/year) (p < 10⁻⁶). Two hundred two (71.6%) stings occurred inside human dwellings, 142 (50.4%) during sleeping/resting, especially in August. One hundred ninety-one (67.7%) were on the lower extremities. Nocturnal stings, 168 (59.6%), occurred more often than diurnal stings, 114 (40.4%). Most patients, 163 (57.8%), were admitted less than 1 h after being stung. Local pain at the sting site was the common primary complaint. However, moderate and severe clinical signs were significantly higher in children than in adults (p < 0.05). The death rate (3.9%) was higher in children (3.5%) than in adults (0.3%) (p = 8.10⁻⁶; RR = 0.90 [IC: 0.84-0.06]). Of the 22 scorpion species identified, 13 (59.1%) were Leiurus quinquestriiatus, 8 (36.4%) were Androctonus amoreuxi, and 1 (4.5%) specimen was Buthiscus bicalcaratus. From these species, L. quinquestriiatus and A. amoreuxi were responsible of stings. The medical treatment was only symptomatic, and one hundred twenty-eight (45.3%) patients received traditional remedies before seeking medical attention. Our findings suggest that scorpion stings are common in the north of Mali and are a significant threat to human health.     

Corticosterone in relation to tissue cadmium, mercury and selenium concentrations and social status of male lesser scaup (Aythya affinis)

Combined lesser scaup (Aythya affinis) and greater scaup (A. marila) populations have declined steadily from the 1970s. Accompanying the population decline have been two shifts in lesser scaup demographics: a decrease in the proportion of young birds and an increase in male to female ratio. In addition, there are concerns about potential effects of contaminants and trace elements. These metals may influence the stress response and corticosterone secretion. We examined impacts of cadmium, selenium and mercury on the stress response in relation to social status in male lesser scaup near Yellowknife, NWT May to June 2004 and 2005. Kidney cadmium and liver selenium and mercury ranged 0.78–93.6, 2.12–9.64, and 0.56–3.71 μg/g, dry weight, respectively. Results suggest that corticosterone release may be influenced by complex contaminant interactions in relation to body condition and body size. When cadmium was high and birds were in good body condition, there was a negative relationship between liver selenium and corticosterone (R ² = 0.60, n = 10, P = 0.008) but not in birds with poor body condition (R ² = 0.07, n = 9, P = 0.50). Unfortunately we were unable to draw any conclusions about metals and social status in relation to corticosterone or glucose and T₄. This study emphasizes the complex nature of biological systems and the importance of considering interactions to characterize effects of metals.     

Source and trophic transfer of mercury in plankton from an ultraoligotrophic lacustrine system (Lake Nahuel Huapi,North Patagonia)

The incorporation and trophic transfer of total and methyl mercury (THg, MeHg) were examined in three size classes of plankton (10–53, 53–200, and >200 μm size range) and a small planktivorous fish, Galaxias maculatus, from the large multi-branched Lake Nahuel Huapi (North Patagonia, Argentina). Three sites representing a large range of lake benthic–pelagic structures (based on depth and shoreline characteristics) and precipitation regimes were sampled. Nitrogen and carbon stable isotopes (δ¹⁵N, δ¹³C) were analyzed to assess Hg trophodynamics. Selenium concentrations were determined together with THg in order to consider its potential effect on Hg trophodynamics. High THg concentrations (0.1–255 µg g^?1 dry weight (DW)) were measured in plankton, largely in inorganic form (MeHg: 3–29 ng g^?1 DW, 0.02–7 % of THg, in the two larger size classes). A trend of increasing THg concentrations, varying in two to three orders of magnitude, with decreasing plankton size was associated with precipitation measured prior to each sampling event. Passive adsorption of dissolved Hg²⁺ from wet deposition and runoff is considered to be the principal Hg uptake mechanism at the base of the pelagic food web. Despite the initially high THg uptake in the smaller plankton classes, the transfer to G. maculatus, and consequently to the entire food web, is likely limited due to low proportion of MeHg to THg in plankton. Furthermore, evidence of G. maculatus with benthic feeding habits having higher impact on MeHg trophic transfer compared to the same species with more pelagic (e.g., zooplankton) feeding habits, was observed. Although there is a high THg uptake in plankton, limited amounts are incorporated in the entire food web from the pelagic compartment.     

肾移植术后环孢素A血药浓度与肝毒性的关系

目的研究肾移植术后用环孢素(CsA)为主的免疫抑制剂治疗的患者CsA血药浓度和CsA致肝毒性的关系。方法分别用单克隆荧光偏振免疫分析法测定肾移植术后患者环孢素全血浓度;同时,酶速率法、酶循环及比色法监测丙氨酸氨基转移酶(ALT)活力及血清总胆红素(TBiL)、总胆汁酸(TBA)等肝功能指标。结果术前肝功能正常的46例肾移植受者中,确诊有16人发生了环孢素致药物性肝功能损害。结论移植术后应用环孢素的患者应密切监测CsA的血药浓度,并结合临床肝功能指标,调整环孢素的用量,以避免或减轻肝中毒。     

Hepatic and renal clearances of probenecid in the rat

The elimination kinetics of probenecid in the rat was studied by using an in vitro liver perfusion system to estimate its basic elimination and in vivo to estimate its renal excretion by catheterization of the urinary bladder. In the liver perfusion study different amounts of probenecid were added to the perfusion medium yielding different initial concentrations (40, 200 and 400 micrograms/ml), and 4 different intravenous bolus doses (50, 75, 100 and 200 mg/kg) were administered in vivo to rats in order to evaluate the renal excretion. The results obtained were described by one-compartment models, with Michaelis-Menten elimination by the liver Vm = 67.4 +/- 14.0 (SD) micrograms/min and a slightly decreasing Km with increasing initial concentrations [from 76.5 +/- 9.0 to 53.2 +/- (SD) 18.4 micrograms/ml]. The excretion by the kidney was characterized by a saturable pathway in parallel with first-order elimination, the maximum rate of the active transports Tm = 0.04 +/- (SD) 0.09 micrograms/min, Km,r = 100.3 +/- (SD) 12.3 micrograms/ml and a linear renal clearance of 0.0008 +/- (SD) 0.0002 ml/min.     

High-dose methylprednisolone sodium succinate (pulse therapy) in the treatment of renal disease: Plasma and urine concentrations

Summary Methylprednisolone hemisuccinate (MPS) and methylprednisolone (MP) concentrations in plasma and urine were monitored in renal transplant and glomerulonephritis patients who were given i.v. infusions of 0.5 g or 1 g of MPS. A marked individual variation of peak plasma levels of both MPS and MP was observed after the same dose and MPS disappeared from plasma more rapidly than MP. Their clearances from the circulation, however, did not appear to be significantly influenced by the peak plasma levels of the drug, creatinine clearance, administration of previous pulses of MPS or the urinary excretion of unconjugated MPS and MP. Even in patients with profoundly reduced renal function, no accumulation of the drug was apparent when repeated doses of MPS were administered at 48-h intervals.     

Biomarker responses in the bivalve (Chlamys farreri) to exposure of the environmentally relevant concentrations of lead, mercury, copper

Water samples collected from Bohai Bay were determined to describe the distributions of lead, mercury, and copper in this area, indicating that mean values of the three metals were 1.63μg/L, 4.85×10(-2)μg/L, and 2.68μg/L, respectively. Only lead exceeded the first class limit of seawater quality standard in China. Then, antioxidant enzymes, lipid peroxidation, and metabolic enzymes were investigated in bivalves (Chlamys farreri), exposed to three metals at the environmental concentration levels obtained from our investigation. Significantly reduced SOD, CAT and GPx activities, in lead-exposed group were observed and resulted in obvious lipid peroxidation. In contrast, mercury and copper did not show such clear oxidative stresses. In consistent with the oxidative stress variations, exposed only to lead caused a great inhibition on EROD activity. Multi-biomarker responses in bivalve when exposed to lead at the environmentally relevant concentration in Bohai Bay suggested that lead may possess a potential risk in this area.     

Examination of the behavior and liver and thyroid histology of juvenile rainbow trout (Oncorhynchus mykiss) exposed to high dietary concentrations of C(10)-, C(11)-, C(12)- and C(14)-polychlorinated n-alkanes.

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to high dietary concentrations of six polychlorinated n-alkane (PCAs) (C(10)H(15.5)C(6.5), C(10)H(15.3)Cl(6.7),C(11)H(18.4)Cl(5.6),C(12)H(19.5)Cl(6.5),C(14)H(24.9)Cl(5.1) and C(14)H(23.3)Cl(6.7)) for 21 to assess their effects on behavior and liver and thyroid histology and for 85 days to assess histology for a longer term exposure. This is the first histological work using PCAs of known carbon chain length and chlorine content and the first effort to examine the histopathology of fish exposed to PCAs. PCAs, also known as chlorinated paraffins, are complex industrial products for which there is a lack of toxicological data on individual congeners. With the exception of trout exposed to C(14)H(24.9)Cl(5.1), which had much lower exposure concentrations, many of the trout exposed to the PCAs (whole fish concentrations 0.22-5.5 microg g(-1)) showed a diminished or no startle response, loss of equilibrium, and developed a dark coloration. These responses are indicative of a narcotic toxicological mode-of-action. Histopathological lesions were observed in the livers of trout from each exposure group. However, the most severe histopathologies were observed in the livers of fish exposed to C(10)H(15.3)Cl(6.7) and C(11)H(18.4)Cl(5.6) (whole fish concentrations 0.92 and 5.5 microg g(-1), respectively), in which extensive fibrous lesions were present that were not observed in any other exposure group. Other alterations observed in all treatment groups included hepatocyte necrosis, sites of inflammation, and glycogen/lipid depletion. The relative sizes of hepatocytes of PCA exposed trout were smaller than control trout, although only a few of the observed differences were statistically significant. No lesions were present in the thyroid, although trout exposed to C(10)H(15.5)Cl(6.5) (whole fish concentration 0.84 microg g(-1)) had slightly more active thyroids, as indicated by an increased mean thyroid epithelium cell height relative to controls. It would appear that PCA toxicity is inversely related to carbon chain length, as has been observed in similar studies using mammals. The concentrations in the fish from this experiment were at levels that have been reported in invertebrates and fish from contaminated sites in the Great Lakes. However, the exposure concentrations were likely much greater in these experiments compared with the environment and require further study.