Endogenous creatinine in serum and urine

Changes of markers of oxidative stress during menstrual cycle

The levels of urinary hydrogen peroxide and thiobarbituric acid reactive substances have been compared during the menstrual cycle of 12 regularly menstruating women. Higher level of both indices of oxidative stress (normalized with respect to creatinine content) were found in the luteal phase of the cycle. These results give further evidence for the usefulness of urinary hydrogen peroxide and thiobarbituric acid reactive substances as potential biomarkers of oxidative stress and for the antioxidant action of estrogens.

Creatinine versus specific gravity-adjusted urinary cadmium concentrations

The aim was to assess how urinary creatinine is affected by age, gender, body size and meat intake, and to determine to what extent such factors might affect the creatinine adjustment of urinary cadmium. The study was based on three Swedish studies: (1) 67 non-smoking women aged 20-50 years (24-h urine samples); (2) 289 men and 434 women aged 16-81 years (spot urine samples); and (3) 98 men and 105 women aged 19-72 years (spot urine samples). The effects of age, body surface area (as an indicator of muscle mass), and meat intake on urinary creatinine and cadmium were analysed using multiple regression analyses. Gender- and age-related variations in urinary creatinine and cadmium adjusted for creatinine or specific gravity were compared by ANOVA or ANCOVA. In the multiple regression analyses, body surface area, gender, age and meat intake were the major determinants of urinary creatinine. Urinary cadmium adjusted for creatinine and specific gravity were also dependent on body size, gender and age. Urinary cadmium adjusted for creatinine was 15-92% higher in women or older individuals than in men or younger individuals. Women or older individuals had -3 to 79% higher urinary cadmium adjusted for specific gravity than men or younger individuals had, and such a difference between gender or age group was less obvious in specific gravity adjustment than in creatinine adjustment. Thus, urinary cadmium adjusted for creatinine is more affected by age, gender, body size and meat intake than is specific gravity adjustment. When comparing individuals or populations with large differences in muscle mass or meat intake, such effects can be especially important. In such studies, specific gravity adjustment seems to be more appropriate.

Renal effects evolution in a Chinese population after reduction of cadmium exposure in rice

Cadmium is a well-known nephrotoxic agent with extremely long biological half-time of 10-30 years in human. To investigate the evolution of cadmium-induced renal effects in the population, a number of 148 residents who lived in cadmium-polluted area were followed-up for 3 years after the reduction of cadmium exposure in rice. Urinary cadmium (UCd), beta(2)-microglobulin (B2M) and albumin (ALB) were analyzed in 1995 and 1998, respectively. The results demonstrated that the changes of renal effects of residents depended on the levels of UCd before inflow of cadmium to human body declined. In cases where UCd were less than 10 microg/g creatinine in 1995, evidence was found indicating significant decreases in proteinuria (i.e., B2M and ALB) 3 years later, whereas, in cases where the excretion of UCd exceeded 10 microg/g creatinine in 1995, progression was observed. The study of dose-response relationships between UCd and B2M or ALB also showed that the cadmium-induced renal dysfunction might be reversible if UCd concentration was low-level before exposure decreasing, otherwise it might be irreversible or aggravated.

High basal metabolic rate is a risk factor for mortality: the Baltimore Longitudinal Study of Aging

BACKGROUND

Despite longstanding controversies from animal studies on the relationship between basal metabolic rate (BMR) and longevity, whether BMR is a risk factor for mortality has never been tested in humans. We evaluate the longitudinal changes in BMR and the relationship between BMR and mortality in the Baltimore Longitudinal Study of Aging (BLSA) participants.

METHODS

BMR and medical information were collected at the study entry and approximately every 2 years in 1227 participants (972 men) over a 40-year follow-up. BMR, expressed as kcal/m(2)/h, was estimated from the basal O(2) consumption and CO(2) production measured by open-circuit method. Data on all-cause and specific-cause mortality were also obtained.

RESULT

BMR declined with age at a rate that accelerated at older ages. Independent of age, participants who died had a higher BMR compared to those who survived. BMR was a significant risk factor for mortality independent of secular trends in mortality and other well-recognized risk factors for mortality, such as age, body mass index, smoking, white blood cell count, and diabetes. BMR was nonlinearly associated with mortality. The lowest mortality rate was found in the BMR range 31.3-33.9 kcal/m(2)/h. Participants with BMR in the range 33.9-36.4 kcal/m(2)/h and above the threshold of 36.4 kcal/m(2)/h experienced 28% (hazard ratio: 1.28; 95% confidence interval, 1.02-1.61) and 53% (hazard ratio: 1.53; 95% confidence interval, 1.19-1.96) higher mortality risk compared to participants with BMR 31.3-33.9 kcal/m(2)/h.

CONCLUSION

We confirm previous findings of an age-related decline of BMR. In our study, a blunted age-related decline in BMR was associated with higher mortality, suggesting that such condition reflects poor health status.

Osteoporosis in a Chinese population due to occupational exposure to lead

BACKGROUND

Recent studies indicate that lead may exert actions both directly on osteoblast and osteoclast function, and indirectly via kidney dysfunction on bone turnover. The main focus of this study was to investigate whether occupational lead exposure is associated with low bone mass in a population working in a storage battery plant.

METHODS

Monophoton absorptiometry was used to measure bone mineral density (BMD) in the population and the Z score was introduced to define osteoporosis (Z score <-2). Lead concentration of urine and blood was determined by graphite-furnace atomic absorption spectrophotometry as an exposure biomarker. A total of 249 persons (191 males and 58 females) participated and completed a questionnaire in order to obtain information on height, weight, age, medical and drug history, cigarette smoking, alcohol consumption, job position, work year, physical exercise, etc.

RESULTS

The BMD was significantly decreased in the groups of the high urinary lead (UPb) level compared with the low UPb level with a significant difference (P < 0.05) in both genders, but no such significant difference was observed in the relationship between blood lead (BPb) and BMD. The prevalence of osteoporosis would increase significantly with the increase of the UPb (P < 0.01) in the linear correlation manner (P < 0.01). There was also such a significant relationship between BPb and osteoporosis (P < 0.01). There was a dose-response relationship between lead exposure and prevalence of osteoporosis.

CONCLUSIONS

In contrast to BPb, UPb had a more close relationship with osteoporosis caused by lead. It was concluded that occupational exposure to lead is associated with osteoporosis.

Urinary arsenic concentration adjustment factors and malnutrition

This study aims at evaluating the suitability of adjusting urinary concentrations of arsenic, or any other urinary biomarker, for variations in urine dilution by creatinine and specific gravity in a malnourished population. We measured the concentrations of metabolites of inorganic arsenic, creatinine and specific gravity in spot urine samples collected from 1466 individuals, 5-88 years of age, in Matlab, rural Bangladesh, where arsenic-contaminated drinking water and malnutrition are prevalent (about 30% of the adults had body mass index (BMI) below 18.5 kg/m(2)). The urinary concentrations of creatinine were low; on average 0.55 g/L in the adolescents and adults and about 0.35 g/L in the 5-12 years old children. Therefore, adjustment by creatinine gave much higher numerical values for the urinary arsenic concentrations than did the corresponding data expressed as microg/L, adjusted by specific gravity. As evaluated by multiple regression analyses, urinary creatinine, adjusted by specific gravity, was more affected by body size, age, gender and season than was specific gravity. Furthermore, urinary creatinine was found to be significantly associated with urinary arsenic, which further disqualifies the creatinine adjustment.

Gender and age differences in the metabolism of inorganic arsenic in a highly exposed population in Bangladesh

Although genetic polymorphisms have been shown to explain some of the large variation observed in the metabolism of inorganic arsenic there may be several other factors playing an important role, e.g. nutrition. The objective of this study was to elucidate the influence of various factors on current arsenic exposure and metabolism in Matlab, a rural area in Bangladesh, where elevated water arsenic concentrations and malnutrition are prevalent. In total 1571 individuals, randomly selected from all inhabitants above 5 years of age, were investigated by measuring arsenic in urine and drinking water. In a subset of 526 randomly selected individuals, arsenic metabolites were speciated using HPLC coupled to inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS). A significant association was observed between arsenic in urine and drinking water (R2=0.41). The contribution to urinary arsenic from arsenic exposure from food and other water sources was calculated to be almost 50microg/L. The individuals in the present study had remarkably efficient methylation, in spite of high exposure and prevalence of malnutrition. Gender and age were major factors influencing arsenic metabolism in this population with a median of 77microg/L of arsenic in urine (range: 0.5-1994microg/L). Women had higher arsenic methylation efficiency than men, but only in childbearing age, supporting an influence of sex hormones. Overall, exposure level of arsenic, gender and age explained at most 30% of the variation in the present study, indicating that genetic polymorphisms are the most important factor influencing the metabolism of inorganic arsenic.

Perillyl Alcohol Protects Against Fe-NTA-Induced Nephrotoxicity and Early Tumor Promotional Events in Rat Experimental Model

Plants have been widely used as protective agents against a wide variety of processes and compounds that damage tissues via free radical mechanisms. Perillyl alcohol (PA) is a naturally occurring monoterpene found in the essential oils of numerous species of plants including mints, cherries and celery seeds. This monocyclic monoterpene has shown antioxidant and therapeutic activity in various studies against various xenobiotics. In this study, we have analyzed the effects of PA against single intraperitoneal dose of ferric nitrilotriacetate (Fe-NTA) (9 mg iron per kg body weight)-induced nephrotoxicity and early tumor promotional events. The pretreatment of Fe-NTA-treated rats with 0.5% per kg body weight dose and 1% per kg body weight dose of PA for seven consecutive days significantly reversed the Fe-NTA-induced malondialdehyde formation, xanthine oxidase activity (P < 0.001), ornithine decarboxylase activity (P < 0.001) and (3)[H]thymidine incorporation in renal DNA (P < 0.001) with simultaneous significant depletion in serum toxicity markers blood urea nitrogen and creatinine (P < 0.001). Significant restoration at both the doses was recorded in depleted renal glutathione content, and its dependent enzymes with prophylactic treatment of PA. Present results suggest that PA potentially attenuates against Fe-NTA-induced oxidative damage and tumor promotional events that preclude its development as a future drug to avert the free radical-induced toxicity.

Eruca sativa seeds possess antioxidant activity and exert a protective effect on mercuric chloride induced renal toxicity

Mercuric chloride (HgCl(2)) is a well-known nephrotoxic agent. Increasing number of evidences suggest the role of oxidative stress in HgCl(2) induced nephrotoxicity. Eruca sativa is widely used in folklore medicines and has a good reputation as a remedy of renal ailments. In the present study, the antioxidant potential of ethanolic extract of E. sativa seeds was determined and its protective effect on HgCl(2) induced renal toxicity was investigated. The extract was found to possess a potent antioxidant effect, with a large amount of polyphenols and a high reducing ability. HPLC analysis of the extract revealed glucoerucin and flavonoids to be the major antioxidants present in it. E. sativa extract significantly scavenged several reactive oxygen species (ROS) and reactive nitrogen species (RNS). Feeding of the extract to rats afforded a significant protection against HgCl(2) induced renal toxicity. Subcutaneous administration of 4 mg/kg body weight HgCl(2) induced renal injury evident as a marked elevation in serum creatinine and blood urea nitrogen levels, and histopathological changes such as necrosis, oedema and congestion of stroma and glomeruli. Oxidative modulation of renal tissues following HgCl(2) exposure was evident from a significant elevation in lipid peroxidation and attenuation in glutathione (GSH) contents and activities of antioxidant enzymes viz., catalase (CAT), glutathione peroxidase (GPX), superoxide dismutase (SOD) and glutathione reductase (GR). Oral administration of E. sativa extract to rats at a dose regimen: 50-200 mg/kg body weight for 7 days prior to HgCl(2) treatment significantly and dose dependently protected against alterations in all these diagnostic parameters. The data obtained in the present study suggests E. sativa seeds to possess a potent antioxidant and renal protective activity and preclude oxidative damage inflicted to the kidney.

Farnesol prevents Fe-NTA-mediated renal oxidative stress and early tumour promotion markers in rats

Excess iron deposition in tissues leads to organ dysfunction and impairment. In this study, the protective effects of farnesol (FL), an isoprenoid, against Fe-NTA (9 mg iron/kg body weight i.p.)-induced oxidative damage and early tumour promotion markers are evaluated. The pretreatment of iron-intoxicated rats with 1% and 2%/kg body weight oral dose of FL for 7 consecutive days significantly reversed the iron-induced increase in H2O2 content (P < 0.001), malondialdehyde formation, xanthine oxidase activity (P < 0.001), ornithine decarboxylase activity (P < 0.001) and 3[H]thymidine incorporation in renal DNA (P < 0.005) with simultaneous significant depletion in serum toxicity markers blood urea nitrogen (BUN) and creatinine (P < 0.001). Significant dose-dependent restoration was recorded in renal glutathione content, its dependent enzymes and other phase II metabolizing enzymes viz., catalase, glutathione-S-transferase and quinone reductase (P < 0.001) with prophylactic treatment of FL. Present results support that FL markedly lowers the oxidative damage and appearance of tumour markers, which precludes its development as a chemopreventive tool.

Modulatory Effects of Shape Pluchea Lanceolata Against Chemically Induced Oxidative Damage, Hyperproliferation And Two-Stage Renal Carcinogenesis in Wistar Rats

Ferric nitrilotriacetate (Fe-NTA) is a well-established renal carcinogen. Here, we have shown that Pluchea lanceolata (PL) belonging to the family Asteraceae. PL attenuates Fe-NTA induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in rats. It promoted DEN (N-diethyl nitrosamine) initiated renal carcinogenesis by increasing the percentage incidence of tumors and induces early tumor markers viz. ornithine decarboxylase (ODC) and renal DNA synthesis. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) also enhances renal lipid peroxidation (LPO), xanthine oxidase (XO) and hydrogen peroxide (H(2)O(2)) generation with reduction in renal glutathione content (GSH), antioxidant enzymes, viz., glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), glucose-6-phosphate dehydrogenase and phase-II metabolizing enzymes such as glutathione-S-transferase and quinone reductase (QR). It also enhances blood urea nitrogen (BUN) and serum creatinine. Oral treatment of rats with PL extract (100 and 200 mg/kg body weight) resulted in significant decrease in lipid peroxidation (LPO), xanthine oxidase (XO), H(2)O(2) generation, blood urea nitrogen (BUN), serum creatinine, renal ODC activity, DNA synthesis (p < 0.001) and incidence of tumors. Renal glutathione content (p < 0.01), its metabolizing enzymes (p < 0.001) and antioxidant enzymes were also recovered to significant level (p < 0.001). Thus, present study supports PL as a potent chemopreventive agent and suppresses Fe-NTA-induced renal carcinogenesis and oxidative damage response in Wistar rat.

Chemomodulatory effects of Terminalia chebula against nickel chloride induced oxidative stress and tumor promotion response in male Wistar rats

Nickel, a major environmental pollutant is a known potent nephrotoxic agent. In this communication we report the chemopreventive effect of Terminalia chebula on nickel chloride (NiCl(2)) induced renal oxidative stress, toxicity and cell proliferation response in male Wistar rats. Administration of NiCl(2) (250micromoL Ni/kg body weight) to male Wistar rats resulted in an increase in the reduced renal glutathione content (GSH), glutathione-S-transferase (GST), glutathione reductase (GR), lipid peroxidation (LPO), H(2)O(2) generation, blood urea nitrogen (BUN) and serum creatinine with a concomitant decrease in the activity of glutathione peroxidase (p<0.001). Nickel chloride (NiCl(2)) treatment also induced tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [(3)H] incorporation into renal DNA (p<0.001). Prophylactic treatment of rats with T. chebula (25mg/kg body weight and 50mg/kg body weight) daily for one week resulted in the diminution of NiCl(2) mediated damage as evident from the down regulation of glutathione content, GST, GR, LPO, H(2)O(2) generation, BUN, serum creatinine, DNA synthesis (p<0.001) and ODC activity (p<0.01) with concomitant restoration of GPx activity. Thus, the present investigation suggests that T. chebula extract could be used as therapeutic agent for cancer prevention as evident from this study where it blocks or suppresses the events associated with chemical carcinogenesis.

Inhibition of potassium bromate-induced renal oxidative stress and hyperproliferative response by Nymphaea alba in Wistar rats

KBrO3-mediated renal injury and hyperproliferative response in Wistar rats. In this communication, we report the efficacy of Nymphaea alba on KBrO3 (125 mg/kg body weight, intraperitoneally) caused reduction in renal glutathione content, renal antioxidant enzymes and phase-II metabolising enzymes with enhancement in xanthine oxidase, lipid peroxidation, gamma-glutamyl transpeptidase and hydrogen peroxide (H202). It also induced blood urea nitrogen, serum creatinine and tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and DNA synthesis. Treatment of rats with Nymphaea alba (100 and 200 mg/kg body weight) one hour before KBrO3 (125 mg/kg body weight, i.p.) resulted in significant decreases in xanthine oxidase (P < 0.05), lipid peroxidation, gamma-glutamyl transpeptidase, H202 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Renal glutathione content, glutathione metabolizing enzymes and antioxidant enzymes were also recovered to significant levels (P < 0.001). These results show that Nymphaea alba acts as chemopreventive agent against KBrO3-mediated renal injury and hyperproliferative response.

Modulatory Effect of Ficus racemosa: Diminution of Potassium Bromate-Induced Renal Oxidative Injury and Cell Proliferation Response

The aim of the present study was to determine the potential beneficial effects of Ficus racemosa extract. Potassium bromate (KBrO3), a potent nephrotoxic agent that induces renal carcinogenesis and acts as tumour promoter in carcinogen-initiated animals was used as a model to induce renal injury. In this study, we show the chemopreventive effect of Ficus racemosa extract (Moraceae) on KBrO3-mediated renal oxidative stress and cell promotion response in rats. KBrO3 (125 mg/kg body weight, intraperitoneally) enhanced lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content and antioxidant enzymes. KBrO3 treatment also induced tumour promotion markers, viz., ornithine decarboxylase activity and thymidine [3H] incorporation into renal DNA. A sharp elevation in the levels of blood urea nitrogen and serum creatinine has also been observed. Treatment of rats orally with Ficus racemosa extract (200 mg/kg body weight and 400 mg/kg body weight) resulted in a significant decrease in xanthine oxidase (P<0.05), lipid peroxidation (P<0.001), gamma-glutamyl transpeptidase (P<0.001) and H(2O2 (P<0.001). There was significant recovery of renal glutathione content (P<0.01) and antioxidant enzymes (P<0.001). There was also reversal in the enhancement of renal ornithine decarboxylase activity, DNA synthesis, blood urea nitrogen and serum creatinine (P<0.001). Our results suggest that Ficus racemosa extract is a potent chemopreventive agent and suppresses KBrO3-mediated nephrotoxicity in rats.

Biomarkers of cadmium and arsenic interactions

Advances in proteomics have led to the identification of sensitive urinary biomarkers of renal dysfunction that are increasingly used in toxicology and epidemiology. Recent animal data show that combined exposure to inorganic arsenic (As) and cadmium (Cd) gives rise to more pronounced renal toxicity than exposure to each of the agents alone. In order to examine if similar interaction occurs in humans, renal dysfunction was studied in population groups (619 persons in total) residing in two metal contaminated areas in China: mainly a Cd contaminated area in Zhejiang province (Z-area) and mainly a As contaminated area in Guizhou province (G-area). Nearby control areas without excessive metal exposure were also included. Measurements of urinary beta(2)-microglobulin (UB2MG), N-acetyl-beta-glucosaminidase (UNAG), retinol binding protein (URBP) and albumin (UALB) were used as markers of renal dysfunction. Urinary Cd (UCd) and total As (UTAs) were analyzed by graphite-furnace atomic absorption spectrometry. Urinary inorganic As and its mono- and di-methylated metabolites (UIAs) were determined by Hydride generation. Results. As expected, the highest UCd values occurred in Z-area (Geometric mean, GM 11.6 microg/g crea) while the highest UTAs values occurred in G-area (GM = 288 microg/g crea). Statistically significant increases compared to the respective control area were present both for UTAs, UCd and for UB2MG, UNAG and UALB in Z-area as well as in G-area. UIAs was determined only in Z area. In G-area, there was a clear dose-response pattern both in relation to UTAs and UCd for each of the biomarkers of renal dysfunction. An interaction effect between As and Cd was demonstrated at higher levels of a combined exposure to As and Cd enhancing the effect on the kidney. In Z-area an increased prevalence of B2MG-uria, NAG-uria and ALB-uria was found in relation to UCd, but no relationship to UTAs was found. A statistically significant relationship between UIAs and UB2MG was found among women in this area and an interaction between As and Cd was indicated for B2MG. Conclusion. The present studies, which employed sensitive biomarkers of renal dysfunction, give support to the idea that human co-exposure to Cd and inorganic arsenic gives rise to more pronounced renal damage than exposure to each of the elements alone, but further studies are needed to establish and clarify this interaction.

Vitamin E therapy prevents hyperoxaluria-induced calcium oxalate crystal deposition in the kidney by improving renal tissue antioxidant status

OBJECTIVE

To determine whether vitamin E prevents hyperoxaluria-induced stone formation, using a new animal model of calcium oxalate stone disease, as our previous in- vitro and in-vivo studies showed that oxalate and hyperoxaluria induce free-radical generation, which results in peroxidative injury to renal tubular cells.

MATERIALS AND METHODS

Ethylene glycol (EG) was administered at 150 mg/day by gavage for 3 weeks to rats fed on diets with adequate (group 1), excess (group 2) or deficient (group 3) vitamin E. Several indicators of peroxidation, free radicals and enzymatic activity were then assessed.

RESULTS

EG treatment in group 1 lead to increased lipid peroxidation, protein thiol, excretion of urinary enzymes, oxalate and decreases in urinary calcium, antioxidant enzymes and altered glutathione redox balance. Although renal function was not altered, there was increased water intake, urine volume and lowered urinary pH in these rats. These changes were more intense, with extensive calcium-oxalate crystal deposition, in rats in group 3, and prevented in rats in group 2, except for urinary oxalate levels, which remained high. Histopathological examination showed that there was no deposition of calcium oxalate crystals in rats in group 2.

CONCLUSION

This is the first study to demonstrate in-vivo evidence that hyperoxaluria-induced peroxidative injury induces individual calcium oxalate crystal attachment in the renal tubules. In addition, excess vitamin E completely prevented calcium oxalate deposition, by preventing peroxidative injury and restoring renal tissue antioxidants and glutathione redox balance. Therefore, vitamin E therapy might provide protection against the deposition of calcium oxalate stones in the kidney of humans.

Metallothionein gene expression in peripheral lymphocytes and renal dysfunction in a population environmentally exposed to cadmium

In order to study the validity of metallothionein (MT) gene expression in peripheral blood lymphocytes (PBLs) as a biomarker of cadmium exposure and susceptibility to renal dysfunction, MT mRNA levels were measured using reverse transcription polymerase chain reaction (RT-PCR) in PBLs from residents living in a cadmium-contaminated area. MT mRNA levels were found to increase with the increase of blood cadmium (BCd) and urinary cadmium (UCd) levels. Basal MT mRNA levels were significantly correlated with the logarithm of BCd levels and the logarithm of UCd levels confirming that MT expression in PBLs is a biomarker of cadmium exposure and internal dose. An inverse relationship was observed between in vitro induced MT-mRNA level in PBLs and urinary N-acetyl-beta-d-glucosaminidase (UNAG) suggesting that MT gene expression in PBLs may be used as a biomarker of susceptibility to renal toxicity of cadmium.

Chemomodulatory effect of Ficus racemosa extract against chemically induced renal carcinogenesis and oxidative damage response in Wistar rats

Ferric nitrilotriacetate (Fe-NTA) is a well-known renal carcinogen. In this communication, we show the chemopreventive effect of Ficus racemosa extract against Fe-NTA-induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H(2)O(2)) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. It also enhances blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [(3)H] incorporation into renal DNA. It also enhances DEN (N-diethylnitrosamine) initiated renal carcinogenesis by increasing the percentage incidence of tumors. Treatment of rats orally with F. racemosa extract (200 and 400 mg/kg body weight) resulted in significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H(2)O(2) generation, blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (P<0.001) and incidence of tumors. Renal glutathione content (P<0.01), glutathione metabolizing enzymes (P<0.001) and antioxidant enzymes were also recovered to significant level (P<0.001). Thus, our data suggests that F. racemosa extract is a potent chemopreventive agent and suppresses Fe-NTA-induced renal carcinogenesis and oxidative damage response in Wistar rats.

Inhibition of two stage renal carcinogenesis, oxidative damage and hyperproliferative response by Nigella sativa

In an earlier communication we reported that Nigella sativa suppresses potassium bromate-induced renal oxidative damage. In the present study, we report the chemopreventive effect of Nigella sativa against ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative stress, hyperproliferative response and renal carcinogenesis. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes and phase II metabolizing enzymes. It also caused increase in blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [H] incorporation into renal DNA. It also enhanced DEN (N-diethylnitrosamine)-initiated renal carcinogenesis by increasing the percentage incidence of tumours. Treatment of rats orally with Nigella sativa (50 and 100 mg/kg body weight) resulted in significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (P<0.001) and incidence of tumours. Renal glutathione content (P<0.01), glutathione-metabolizing enzymes (P<0.001) and antioxidant enzymes were also recovered to significant levels (P<0.001). Thus, our data suggest that Nigella sativa is a potent chemopreventive agent and suppresses Fe-NTA-induced oxidative stress, hyperproliferative response and renal carcinogenesis in Wistar rats.

Anticarcinogenic effect of Nymphaea alba against oxidative damage, hyperproliferative response and renal carcinogenesis in Wistar rats

The present study investigates the prophylactic effect of Nymphaea alba against ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in Wistar rats. Treatment with Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhanced iron-ascorbate-induced renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. It also elevated the levels of blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. It also enhanced DEN-initiated renal carcinogenesis by increasing the percentage incidence of renal tumors. Treatment of rats orally with N. alba (100 and 200 mg/kg body weight) resulted in significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (p < 0.001) and incidence of tumors. Renal glutathione content (p < 0.01), glutathione metabolizing enzymes (p < 0.001) and antioxidant enzymes were also recovered to significant level (p < 0.001). Thus, our results show that N. alba is a potent chemopreventive agent and suppresses Fe-NTA-induced oxidative stress, hyperproliferative response and renal carcinogenesis in Wistar rats.

Osteoporosis and renal dysfunction in a general population exposed to cadmium in China

Osteoporosis is a common metabolic disease characterized by low bone mass and microarchitectural deterioration of bone tissue. Many factors are involved in the occurrence of osteoporosis. Cadmium can cause both osteomalacia and osteoporosis and these effects have long been investigated through various epidemiological or experimental studies. The present study examines a possible relationship between cadmium nephropathy and its effects on the skeleton in populations living in a polluted area in southeast China. Monophoton absorptiometry was used to measure bone mineral density in the population and the Z score (the number of SD from the difference between the measured bone density of the individual and the group mean value for sex- and age-matched controls) was introduced to define osteoporosis (Z score < -2). Osteoporosis caused by cadmium exposure was demonstrated in this study on a general population environmentally exposed to cadmium in China. It was found that there were significant differences in the prevalence of osteoporosis among the different urinary cadmium groups (chi2 = 18.84, P = 0.0008). The linear trend test gave chi2 = 16.281, P = 0.00005. There was a dose-response relationship between cadmium exposure (urinary cadmium) and prevalence of osteoporosis. Of 31 subjects with osteoporosis, 23 subjects were suffering from renal dysfunction. The prevalence of renal dysfunction (74.19%) was significantly higher than that in those without osteoporosis (chi2 = 16.53, P < 0.001). Stratum analysis was performed to further assess the relationship between bone damage and renal impairment caused by cadmium. There was a significant difference between those with and without tubular damage (chi2 = 19.92, P = 0.000) but not in those with and without glomerular damage (chi2 = 0.08, P = 0.114). This showed that glomerular dysfunction plays a smaller role than tubular dysfunction in the causation of bone damage. It was found that the prevalence of osteoporosis increases with increasing values of parameters of tubular damage. Osteoporosis caused by cadmium is thus related to kidney dysfunction and especially to tubular damage and its severity but not to glomerular damage. The present study has thus demonstrated the combined adverse effects (osteoporosis and renal dysfunction) caused by environmental exposure to cadmium for the first time in Asia outside the endemic area in Japan.

Abrogation of potassium bromate-induced renal oxidative stress and subsequent cell proliferation response by soy isoflavones in Wistar rats

Potassium bromate (KBrO3) is a potent nephrotoxic agent. In this study, we show the modulatory effect of soy isoflavones on KBrO3-mediated renal oxidative stress and subsequent cell proliferation response in Wistar rats. KBrO3 (125 mg/kg body weight, intraperitoneally) caused reduction in renal glutathione content, activities of renal anti-oxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase with enhancement in xanthine oxidase, lipid peroxidation, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2). KBrO3 treatment also induced blood urea nitrogen, serum creatinine and tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. Treatment of rats orally with soy isoflavones (5 mg/kg body weight and 10 mg/kg body weight) resulted in a significant decrease in xanthine oxidase (P < 0.05), lipid peroxidation, gamma-glutamyl transpeptidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). There was also significant recovery of renal glutathione content (P < 0.01), anti-oxidant enzymes and phase-II metabolising enzymes (P < 0.001). Thus, our results show that soy isoflavones acts as potent chemopreventive agent against KBrO3-mediated renal oxidative stress, toxicity and subsequent cell proliferation response in Wistar rats.

Induction of renal oxidative stress and cell proliferation response by ferric nitrilotriacetate (Fe-NTA): diminution by soy isoflavones

Ferric nitrilotriacetate (Fe-NTA) is a known potent nephrotoxic agent. In this communication, we report the chemopreventive effect of soy isoflavones on renal oxidative stress, toxicity and cell proliferation response in Wistar rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances gamma-glutamyl transpeptidase, renal lipid peroxidation, xanthine oxidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. Fe-NTA treatment also induced tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. A sharp elevation in the levels of blood urea nitrogen and serum creatinine has also been observed. Treatment of rats orally with soy isoflavones (5 mg/kg body weight and 10 mg/kg body weight) resulted in significant decreases in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Renal glutathione content (P < 0.01), glutathione metabolizing enzymes (P < 0.001) and antioxidant enzymes were also returned to normal levels (P < 0.001). Thus, our data suggest that soy isoflavones may be used as an effective chemopreventive agent against Fe-NTA-mediated renal oxidative stress, toxicity and cell proliferation response in Wistar rats.

Amelioration of ferric nitrilotriacetate (Fe-NTA) induced renal oxidative stress and tumor promotion response by coumarin (1,2-benzopyrone) in Wistar rats

In this study, we report the modulatory effect of coumarin (1,2-benzopyrone) on Ferric nitrilotriacetate (Fe-NTA) induced renal oxidative stress and tumor promotion response in rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2) generation with reduction in antioxidant enzymes and renal glutathione content. It also enhances blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. Prophylactic treatment of rats with coumarin (10 and 20 mg/kg body weight) resulted in significant recovery of antioxidant enzymes (P < 0.001) and renal glutathione content (P < 0.01). There was also significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001) Thus, our results show that coumarin is a potent chemopreventive agent and suppresses Fe-NTA induced nephrotoxicity in Wistar rats.

L-carnitine transport in kidney of normotensive, Wistar-Kyoto rats: effect of chronic L-carnitine administration

PURPOSE

To examine the effect of long-term administration of L-carnitine on L-carnitine transport in renal brush-border membrane vesicles (BBMVs) from normotensive, Wistar-Kyoto rats.

METHODS

Rats (n = 20) were orally administered 0.2 g carnitine/kg body weight per day for a total period of 8 weeks. Kinetic parameters of L-carnitine uptake were calculated by non-linear regression, and the relative abundance of the carnitine transporter, OCTN2, was determined by Western blot analysis.

RESULTS

Initial rates and maximal overshoot levels of Na+-dependent L-carnitine transport were significantly reduced in BBMVs from L-carnitine-treated rats compared with untreated animals. Similarly, the maximal transport rate (Vmax) of OCTN2 was lower in treated rats. However, no differences were observed in the Michaelis constant (Km) or the diffusion constant (Kd) between the two groups of animals. The amount of OCTN2 protein was also decreased in L-carnitine-fed rats, this reduction being similar to that of the Vmax. These results were accompanied by an increase in the serum levels and also in the renal excretion of both free and esterified carnitine in treated rats, indicating that the long-term administration of L-carnitine leads to increased renal carnitine clearance.

CONCLUSION

These findings suggest a downregulation of OCTN2 at the renal level, in the presence of high levels of carnitine.

Nigella sativa (black cumin) ameliorates potassium bromate-induced early events of carcinogenesis: diminution of oxidative stress

Potassium bromate (KBrO3) is a potent nephrotoxic agent. In this paper, we report the chemopreventive effect of Nigella sativa (black cumin) on KBrO3-mediated renal oxidative stress, toxicity and tumor promotion response in rats. KBrO3 (125 mg/kg body weight, intraperitoneally) enhances lipid peroxidation, gamma-glutamyl transpeptidase, hydrogen peroxide and xanthine oxidase with reduction in the activities of renal antioxidant enzymes and renal glutathione content. A marked increase in blood urea nitrogen and serum creatinine has also been observed. KBrO3 treatment also enhances ornithine decarboxylase (ODC) activity and [3H] thymidine incorporation into renal DNA. Prophylaxis of rats orally with Nigella sativa extract (50 mg/kg body weight and 100 mg/kg body weight) resulted in a significant decrease in renal microsomal lipid peroxidation (P < 0.001), gamma-glutamyl transpeptidase (P < 0.001), H2O2 (P < 0.001) and xanthine oxidase (P < 0.05). There was significant recovery of renal glutathione content (P < 0.01) and antioxidant enzymes (P < 0.001). There was also reversal in the enhancement of blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Data suggest that Nigella sativa is a potent chemopreventive agent and may suppress KBrO3-mediated renal oxidative stress, toxicity and tumour promotion response in rats.

Alterations of serum hormone levels in male workers occupationally exposed to cadmium

In order to investigate the influence of occupational exposure to cadmium (Cd) on the levels of serum hormone, a cross-sectional study was undertaken in male workers. Creatinine-adjusted urinary cadmium (UCd) was used as the indicator of cadmium body burden in workers. The levels of serum testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined by radioimmunoassay and enzyme immunoassay, respectively. The results showed that with cadmium exposure, the levels of serum testosterone and LH were significantly increased after controlling for confounding factors such as age, smoking habits, and alcohol consumption. However, no significant cadmium-associated changes in the levels of serum FSH were found. At the same time, a significant negative correlation of serum testosterone levels with age was detected. In contrast, the levels of serum FSH and LH were significantly elevated with increasing age. When taking the marital status into consideration, only significantly elevated FSH levels were noted in married workers after controlling for confounding factors. These results indicate that occupational cadmium exposure and other factors such as age and marital status may independently contribute to alterations in the levels of serum sex hormones in males.

Urinary calcium as a biomarker of renal dysfunction in a general population exposed to cadmium

Urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase have been recommended as sensitive indicators of renal dysfunction induced by cadmium. However, an increase in urinary calcium in early renal damage induced by cadmium has been reported both in humans and in animal experiments. To investigate the feasibility of using urinary calcium as a biomarker of renal dysfunction induced by cadmium, two areas were selected in this study, namely, a polluted area with a 3.71 mg/kg cadmium concentration in rice and a control area with a 0.07 mg/kg cadmium concentration. The total number of participants was 499, made up of 252 in the control group and 247 from the cadmium-polluted area. Urinary cadmium, urinary calcium, and zinc concentrations were measured by atomic absorption spectrometry, and beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase in urine were analyzed. The levels of urinary cadmium and urinary calcium in persons from the exposed area were significantly higher (P < 0.05) than those in the control area for both men and women, but there was no significant difference regarding urinary zinc between the two areas. A significant dose-response relationship between the prevalence of hypercalciuria and the excretion of urinary cadmium was observed, and a significantly increased prevalence of calciuria was found when excretion of urinary cadmium exceeded 2 micrograms/g creatinine. The findings were similar to those for excess urinary secretion of beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase. Because cadmium can affect Ca2+ uptake by tubular cells, with decreased renal Ca2+ reabsorption, calciuria may reflect tubular cell damage caused by cadmium. It was concluded that cadmium exposure can result in increased excretion of urinary calcium in a general population and that there is a significant dose-response relationship. Urinary calcium can therefore be used as a biomarker of renal dysfunction induced by cadmium.

Electrophoretic analysis of urinary proteins in diabetic adolescents

Pathological changes in the urine sodium dodecyl sulphate gel electrophoresis (SDS PAGE) patterns often precede the occurrence of any sign of renal involvement in diabetes. However, data concerning the most frequent SDS PAGE pattern of the urine in early stages of type I diabetes mellitus are controversial. In the present study an SDS PAGE technique has been used that provides an adequate sensitivity for the detection of the abnormal pattern. Urinary proteins have been analyzed by SDS PAGE in twenty two diabetic adolescents and twenty four age matched controls. Albumin concentration, and N acetyl-beta-D-glucosaminidase (NAG) activity were also measured in the same samples. There was no significant difference in urine albumin concentration and NAG activity between diabetic children and controls. However twelve patients showed an electrophoretic pattern characteristic for glomerulopathy, two had a pattern indicating tubular dysfunction and another two patients had a mixed pattern. Among the twenty four controls only three showed abnormal electrophoretic patterns. The results support the view that early stages of diabetic nephropathy may involve both glomerular and tubular dysfunction. However the exact clinical and prognostic significance of the information provided by SDS PAGE analysis remains to be elucidated.

Metallothionein gene expression in peripheral lymphocytes from cadmium-exposed workers

Metallothionein (MT) plays an important role in the detoxification of cadmium. To investigate the usefulness of MT gene expression in peripheral blood lymphocytes (PBLs) as a biomarker of cadmium exposure and susceptibility, reverse transcriptase-polymerase chain reaction was used to measure the MT gene expression in PBLs from cadmium-exposed workers. Both basal and induced MT expressions were found to increase with increased blood cadmium (BCd) and urinary cadmium (UCd) levels. Both basal and induced MT expression levels were significantly correlated with the logarithm of BCd and the logarithm of UCd levels. The dose-response relationship between internal dose of cadmium and MT expression suggested the validity of MT expression in PBLs as a biomarker of cadmium exposure. In vitro induced MT expression level in PBLs was found to be inversely related to the level of renal dysfunction indicator, urinary N-acetyl-beta-D-glucosaminidase (UNAG). The latter finding indicates that MT expression in PBLs may be a useful biomarker of susceptibility to renal toxicity of cadmium.