Association of environmental cadmium exposure with inflammation and malnutrition in maintenance haemodialysis patients

BACKGROUND

Chronic inflammation and malnutrition are associated with increased risk of cardiovascular death, and may cause protein-energy wasting in individuals with chronic kidney disease. Raised blood cadmium (Cd) levels were observed in maintenance haemodialysis (HD) patients in previous studies. However, the correlation of Cd exposure with inflammation and malnutrition remains uncertain. This study examined the possible adverse effects of environmental Cd exposure in maintenance HD patients.

METHODS

A total of 954 maintenance HD patients were enrolled and divided into four equal-sized groups based on blood Cd levels. Geographic, haematological, biochemical and dialysis-related data were obtained. The analysis included values for nutritional and inflammatory markers.

RESULTS

Abnormal blood Cd levels (> or =1 microg/L) were exhibited in 26.8% (256/954) of studied subjects. More subjects in the highest quartile group were malnourished (chi- square = 23.27; P < 0.0001) and had inflammatory changes (chi-square = 13.99; P = 0.0029) than in the lowest quartile group. Stepwise multiple regression analysis revealed a significant inverse correlation between serum albumin and blood Cd levels. Notably, a 10-fold increase in blood Cd levels was associated with a 0.06 g/dL decrease in serum albumin levels (P = 0.0060). Multivariate regression analysis also demonstrated a positive correlation between inflammatory risk (high-sensitivity C-reactive protein >3 mg/L) and blood Cd levels. The risk ratio of inflammation with a 10-fold increase in blood Cd levels was 1.388 (95% CI: 1.025-1.825, P = 0.0336).

CONCLUSIONS

Environmental Cd exposure is significantly associated with malnutrition, inflammation and even protein-energy wasting in maintenance HD patients. It is important for this population to avoid diets with high Cd concentrations and smoking.

No effect of cysteine on the pharmacokinetics of intravenous azosemide in rats with protein-calorie malnutrition by pretreatment with 3-methylcholanthrene

The effects of cysteine on the pharmacokinetics of azosemide were investigated after intravenous administration of drug, 10 mg/kg, to male Sprague-Dawley rats pretreated with 3-methylcholanthrene fed on 23% protein diet (control rats) and 5% protein diet without (rats with protein-calorie malnutrition, PCM) or with (rats with PCMC) oral cysteine (250 mg/kg, twice daily starting from the fourth week) for 4 weeks. After intravenous administration to rats with PCM, the metabolites of azosemide excreted in urine and recovered from gastrointestinal tract decreased significantly than those in control rats, however, the plasma concentrations, total area under plasma concentration-time curve from time zero to time infinity (AUC) and time-averaged total body clearance (CL) were not significantly different between two groups of rats. It was reported that after intravenous administration of azosemide, 10 mg/kg, to rats with PCMC without pretreatment 3-methylcholanthrene, some pharmacokinetic parameters restored fully or more than the level of control rats; the time-averaged nonrenal clearance and apparent volume of distribution at steady state were comparable to those in control rats, but the terminal half-life and mean residence time were significantly shorter, AUC was significantly smaller, and time-averaged renal clearance and CL were significantly faster than those in control rats. However, the above mentioned effects of cysteine on the pharmacokinetic parameters of azosemide in rats with PCM were not observed with pretreatment with 3-methylcholanthrene.

The suppressed expression and functional activity of hepatic P-glycoprotein in rats with protein-calorie malnutrition

The effect of protein-calorie malnutrition (PCM) on the expression and functional activity of P-glycoprotein (P-gp) in the liver of rats was examined. Control protein diets and protein-restricted diets were fed to Sprague-Dawley rats for 4 weeks, and the expression of P-gp in the liver (Western blot), in vitro uptake of a representative substrate of P-gp, daunomycin, into canalicular liver plasma membrane (cLPM) vesicles, and in vivo canalicular excretion of daunomycin were compared between the control and PCM rats. The expression of P-gp in the cLPM vesicles was decreased (22%, p < 0.05) by PCM. Consistent with this result, the in vitro uptake rate (V(max)) was decreased (35%, p < 0.05) by PCM, with constant affinity (K(m)), for the carrier-mediated uptake of daunomycin into cLPM vesicles, resulting in a 33% (p < 0.05) decrease in the intrinsic uptake clearance (CL(int)). The in vivo canalicular excretion clearance (CL(exc)) of daunomycin was also decreased by 79% (p < 0.01) in PCM rats, but the degree was more severe than would be expected from the 22% decrease in the expression of P-gp and the 33% decrease in the uptake of daunomycin (CL(int)). The hepatic level of adenosine 5'-triphosphate, which was decreased by 60% (p < 0.01) in PCM rats, might have contributed to this severe decrease in CL(exc). In summary, the canalicular excretion of P-gp substrates, such as daunomycin, might be reduced in patients with PCM via a mechanism involving the suppression of the expression of P-gp.

The effects of nutrition on plasma cholinesterase activity and cocaine toxicity in mice

BACKGROUND

Low plasma cholinesterase activity is associated with severe cocaine toxicity in human subjects and animal experiments. Exogenously enhanced plasma cholinesterase activity is protective against cocaine toxicity in animals. Cocaine users tend to have lower plasma cholinesterase activity than controls. Yet, when cocaine users are allowed to use cocaine in controlled settings without dietary restriction, their plasma cholinesterase activity increases. This study evaluates the influence of diet on plasma cholinesterase activity and cocaine toxicity.

METHODS

Forty-five Swiss albino mice were maintained on a high (30%) protein diet for 3 weeks. They were then randomized into equal groups and given either the high protein diet, an isocaloric low protein diet, or a protein and calorie deficient diet which consisted of reduced intake of the high protein diet. Body weights and plasma cholinesterase activities were measured after a 21-day study period. All animals then received a fixed dose of intraperitoneal cocaine and were observed for seizures and death.

RESULTS

Body weights and plasma cholinesterase activities of the high protein animals remained stable. Weights for the low protein and reduced intake animals fell by 5% and 15%, respectively (p < 0.05 for both vs baseline). Similarly, plasma cholinesterase activities for the low protein and reduced intake animals fell by 4% and 10%, respectively (p = 0.06 for low protein and < 0.05 for reduced intake vs baseline). Cocaine caused seizures in 67% of the high protein animals as compared to 93% and 100% of the low protein and reduced intake animals, respectively (p < 0.05 for high protein vs reduced intake). None of the high protein animals died as compared to 20% and 100% of the low protein and reduced intake animals, respectively (p < 0.05 for high protein vs reduced intake).

CONCLUSION

Protein and calorie malnutrition is associated with a reduction in plasma cholinesterase activity and enhanced cocaine toxicity in mice. Further study is needed to determine if dietary factors are partially responsible for variations in plasma cholinesterase activity and cocaine susceptibility in humans.

Pharmacokinetics of DA-125, a new anthracycline, after intravenous administration to uranyl nitrate-induced acute renal failure rats or protein-calorie malnutrition rats

The pharmacokinetics of DA-125 were compared after intravenous (i.v.) administration of the drug, 10 mg kg-1, to control male Sprague-Dawley rats (n = 9) and uranyl nitrate-induced acute renal failure (U-ARF, n = 12) rats, or male Sprague-Dawley rats fed on a 23% (control, n = 8) or a 5% (protein-calorie malnutrition, PCM, n = 9) protein diet. After i.v. administration of DA-125, almost 'constant' plasma concentrations of M1, M2, and M4 were maintained from 1-2 h to 8-10 h in all rat groups due to the continuous formation of M2 from M1 and M4 from M3. The plasma concentrations of M3 were the lowest among M1-M4 for all rat groups due to the rapid and almost complete conversion of M3 to M4 and other metabolite(s). The AUCt values of M1 (115 against 82.5 micrograms min mL-1), M2 (33.0 against 23.6 micrograms min mL-1), and M4 (26.3 against 15.1 micrograms min mL-1) were significantly higher in the U-ARF rats than in the control rats. The percentages of i.v. dose excreted in 24 h urine as M1 (under the detection limit against 0.316%), M2 (under the detection limit against 5.58%), and M4 (0.0174 against 0.719%)--expressed in terms of DA-125--were significantly lower in the U-ARF rats than in the control rats, and this could be due to the decreased kidney function in the U-ARF rats. However, the percentages of i.v. dose recovered from the GI tract at 24 h as M1 (0.0532% against under the detection limit), M3 (0.0286% against under the detection limit), and M4 (0.702% against 0.305%)--expressed in terms of DA-125--were significantly greater in the U-ARF rats than in the control rats. All U-ARF rats had ascites, but the concentrations of M1 (0.0320 micrograms mL-1), M2 (0.0265 micrograms mL-1), M3 (under the detection limit), and M4 (0.032 micrograms mL-1) in the ascites from one rat were almost negligible. The plasma concentrations and most of the pharmacokinetic parameters of M1, M2, and M4 were not significantly different between the PCM rats and their control rats.

Serum selenium in children during anti-cancer chemotherapy

Serum selenium concentration as an indicator of selenium status was studied during a 6-month period in 24 children with acute leukaemia or solid tumours. At diagnosis low serum selenium values were found in children with acute leukaemia compared to children with solid tumours (P = 0.001), while there were no differences in the protein nutritional status of these children as assessed by serum albumin and prealbumin. During the corticosteroid treatment serum selenium levels increased (mean of 111 per cent) in children with acute leukaemia. The concentrations of serum selenium remained within the reference range of healthy Finnish children from week 16 onwards in children with acute leukaemia and throughout the study period of 24 weeks in children with solid tumours. The results suggest redistribution of the endogenous selenium stores since no selenium supplementation was used, and demonstrate that serum selenium is not a valid indicator of selenium status in these cases.