The effect of levothyroxine replacement therapy on lipid profile and oxidative stress parameters in patients with subclinical hypothyroid.

The purpose of this present study is to investigate the levels of oxidative stress parameters in patients with subclinical hypothyroidism (SH) and the effects of levothyroxine (LT4) replacement therapy on these parameters and lipid profile. At the beginning of the study blood samples were collected from the patients in order to analyse oxidative stress parameters, lipid profile and biochemical markers. After replacement therapy with LT4, in the third month, same tests were performed again. At the baseline superoxide dismutase (SOD) levels were found to be higher in SH patients, compared to the euthyroid group. After LT4 therapy, statistically significant decreases in SOD and catalase levels and increase in HDL-C levels were noticed. LT4 treatment was found to have positive effects on oxidative stress indicators and HDL-C levels.

Occupational exposure of dental technicians to methyl methacrylate: Genotoxicity assessment.

Dental technicians may be chronically exposed to methyl methacrylate (MMA), used in the production of dental prostheses. We have studied whether occupational exposure to MMA affects genotoxicity biomarkers such as 8-OHdG formation, comet assay, and buccal micronucleus frequency. MMA exposure was assessed via ambient air analysis. Although no significant differences between exposed and non-exposed individuals were seen with respect to blood genotoxicity measurements, we found a higher level of buccal-cell anomalies in the exposed group.

Effects of Intermittent and Continuous Magnetic Fields on Trace Element Levels in Guinea Pigs.

Electromagnetic fields (EMFs) can affect living cells due to biochemical changes, followed by changes in levels of trace elements in serum and different organs. This study focuses on the effect of whole body exposure to EMF, presented everywhere in our environment, and on the levels of trace elements in serum, femur, brain, kidney, and liver tissues. The analyses performed on 29 guinea pigs were divided into five groups. Guinea pigs were exposed to a magnetic field of 50 Hz of 1.5 mT. Groups A and B were exposed to the magnetic field for a period of 4 h/day continuously (4 h/day) for 4 and 7 days, respectively. Groups C and D were exposed to the magnetic field for a period of 4 h/day intermittently for 4 and 7 days, respectively. Group E animals were enrolled as control. Copper (Cu), zinc (Zn), calcium (Ca), and magnesium (Mg) levels were determined by atomic absorption spectroscopy in serum, femur, brain, kidney, and liver tissues in all guinea pigs. When compared to the control groups, the changes in the levels of Cu in serum samples, femur, and kidney tissues of the treated groups were statistically significant. The same was also true for the levels of Mg in the brain, kidney, and lung tissues. Our results suggest that in vivo continuous and intermittent exposure to EMF may cause disturbances in homeostasis of bioelements. These effects could be important risk factors for toxic effects of EMF, especially in relation to deterioration of bioelements.

Heavy metal levels in patients with ineffective erythropoiesis.

OBJECTIVES: Iron is taken into enterocytes at the duodenum via apical divalent metal-ion transporter 1 protein. Besides iron, divalent metal-ion transporter 1 also transports other divalent metals. We aimed to investigate blood heavy metal levels in patients with ineffective erythropoiesis. METHODS: Blood levels of heavy metals including Pb, Al, Cd, Cr, Co, Cu, and Zn were measured in patients with thalassemia major (TM), thalassemia intermedia (TI), congenital dyserythropoietic anemia (CDA), and age- and sex-matched healthy controls. RESULTS: Blood samples were obtained from 68 patients (51 patients with TM, 8 with TI, 9 with CDA), and a control group that included 65 volunteers. Patients with TM were found to have lower Al, Pb, and Zn, and higher Cd levels compared with the control group. The patients treated with deferasirox were further analyzed and Pb and Zn levels were found lower compared with the control group. DISCUSSION: Patients with TM had tendency to have elevated levels of plasma cadmium; however, the median level was not at a toxic level. Increased metal-ion transporter 1 activity may cause heavy metal accumulation, but deferasirox chelation may be protective against heavy metals besides iron.

Investigation of the oxidative stress condition for occupational exposure to methyl methacrylate.

The purpose of this study is the evaluation of possible toxicological effects on dental personnel, who are exposed to the production materials of prostheses during their entire working life. In this study, the level of methyl methacrylate (MMA) in ambient air was measured as an indicator of external exposure on the personnel. In order to evaluate the possible toxic effects of oxidative stress, which is thought to play an important role in the formation process of many diseases such as cancer, blood samples of volunteers were examined via the ultraviolet-spectroscopic determination of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase antioxidant enzyme activities, comparing occupationally MMA-exposed ( n = 69) and control ( n = 67) groups. In these groups, malondialdehyde (MDA) and glutathione levels were also determined by the same method. The results showed that SOD activity and MDA and glutathione levels were significantly higher in the exposed group when compared with the control group ( p < 0.001). A significant decrease was determined in the glutathione peroxidase activities of the exposed group ( p < 0.05). No significant difference in CAT activities between the groups has been found. When the results obtained in the study are considered, it is suggested that an adaptive response might be developed by dental technicians against low-level MMA exposure.

In vivo evaluation of the effects of hydraulic calcium silicate dental cements on plasma and liver aluminium levels in rats.

Our aim was to test whether the presence of three hydraulic calcium silicate dental cements--MTA Angelus, MTA Fillapex, and Theracal LC--in the dental extraction socket of an in vivo model, would affect the levels of aluminium (Al) in the plasma and liver. Following anesthesia, the right upper incisor of each male Wistar albino rat was extracted and polyethylene tubes filled with MTA Angelus, MTA Fillapex, or Theracal LC were inserted into the depth of the extraction socket and gingival tissue was sutured. The rats were killed 7, 30, or 60 d after the operation. Blood and liver samples were obtained from the rats before they were killed, and the levels of Al were measured by atomic absorption spectrometry. Plasma Al levels were higher in the rats in which the mineral trioxide aggregate (MTA) cements were implanted, especially MTA Angelus and MTA Fillapex, compared with control rats. In liver samples, however, the differences in Al level were not statistically significant. Our results show that Al might have been released into the circulation from the three dental cements tested, especially MTA Angelus and MTA Fillapex. Further research should be carried out on the possible biological effects of Al liberated from dental cements.

Influence of fetuin and hyaluronan on the post-thaw quality and fertilizing ability of Holstein bull semen.

It was determined that fetuin and hyaluronan supplementation did not provide any significant effect on the post-thaw subjective and CASA motility percentages and sperm motion characteristics, in comparison to the controls (P>0.05). Sperm acrosome and total abnormalities were similar in all groups (P>0.05). Groups M (hyaluronan+fetuin) and H (hyaluronan) displayed a higher rate of sperm membrane integrity, compared to that of Group C (control) (P<0.01). According to the results of the comet assay, the lowest percentage of sperm with damaged DNA was achieved in Group H, when compared to all of the experimental groups (P<0.01). Furthermore, all of the additives resulted in a lower rate of sperm with damaged DNA than that of the controls, and thus, reduced DNA damage (P<0.01). For pregnancy rates, there were no significant differences between the extender groups (P>0.05). MDA formation was found to be lower in Groups M and F (P<0.01). In Group M, SOD activity was determined to have significantly increased (23.61±5.62 U/ml) compared to the other groups (P<0.01). All experimental groups had a GSH-Px activity higher than that of the control group (P<0.01).

Risk assessment of allergen metals in cosmetic products.

Cosmetics are one of the most common reasons for hospital referrals with allergic contact dermatitis. Because of the increased use of cosmetics within the population and an increase in allergy cases, monitoring of heavy metals, especially allergen metals, is crucial. The aim of this study was to investigate the concentration of allergen metals, nickel (Ni), cobalt (Co), and chromium (Cr), in the most commonly used cosmetic products including mascara, eyeliner, eye shadow, lipstick, and nail polish. In addition, for safety assessment of cosmetic products, margin of safety of the metals was evaluated. Forty-eight makeup products were purchased randomly from local markets and large cosmetic stores in Istanbul, Turkey, and an atomic absorption spectrometer was used for metal content determination. Risk assessment of the investigated cosmetic products was performed by calculating the systemic exposure dosage (SED) using Scientific Committee on Consumer Safety guideline. According to the results of this investigation in all the samples tested, at least two of the allergen metals, Ni and/or Co and/or Cr were detected. Moreover, 97% of the Ni-detected products, 96% of Cr- and 54% of Co-detected products, contained over 1 µg/g of this metals, which is the suggested ultimate target value for sensitive population and thereby can be considered as the possible allergen. On the basis of the results of this study, SED of the metals was negligible; however, contact dermatitis caused by cosmetics is most probably due to the allergen metal content of the products. In conclusion, to assess the safety of the finished products, postmarketing vigilance and routine monitoring of allergen metals are very important to protect public health.

Oxidative stress enzyme status and frequency of micronuclei in heroin addicts in Turkey.

Heroin is among the most widely used and dangerous addictive opiate. The World Health Organization (WHO) estimated that more than 15 million people are under the influence of opiate addiction. The aim of this study was to investigate copper zinc-superoxide dismutase (Cu,Zn-SOD), catalase (CAT) and selenium-dependent glutathione peroxidase (Se-GPx) antioxidant enzyme activities, malondialdehyde (MDA) levels and the frequency of micronuclei (MN) in addicts using heroin, the most commonly abused opiate in Turkey. Addicts were defined as individuals diagnosed according to "Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV)" criteria by the "Alcohol and Substance Abuse Treatment and Education Centre-Ankara (AMATEM)". The control group had no addiction. In comparisons between the groups, a significant decrease in Cu,Zn-SOD activity and increases in MDA levels and MN frequency were observed in addicts. It can be concluded that opiates may cause oxidative stress and that antioxidant supplementation, in addition to pharmacological and psychiatric approaches, can reduce the toxicological effects of these opiates.

Effects of smoking during pregnancy on DNA damage and ROS level consequences in maternal and newborns' blood.

Some of the genotoxic/carcinogenic substances or metabolites in cigarette smoke are capable of passing through the placenta and harming a newborn's health. Smoking is also known as a factor in the formation of oxidative damage and the main mechanism involved in the carcinogenic process. Predetermining this genotoxic risk can be successfully achieved by measuring certain parameters of oxidative stress. The comet assay is considered an important biomarker for the evaluation of genotoxic substances and is effective for detecting DNA damage caused by smoking. This study examined third trimester bloods and the cord blood of 28 actively smoking and 22 non-smoking mothers in terms of DNA damage and oxidative stress parameters. Cu/Zn superoxide dismutase (CuZn-SOD), malondialdehyde (MDA), catalase (CAT), plasma nitrite/nitrates (NO2-/NO3-), selenium-dependent glutathione peroxidase (Se-GPx), Cu, and Zn levels were measured as indicators of oxidative damage. There were no significant increases in DNA damage of the actively smoking pregnant group in comparison with the non-smoking pregnant group, either in the third trimester or cord blood. Oxidative stress parameters of smoker and non-smoker groups were statistically different for MDA (p<0.05), CuZn-SOD (p<0.01), Se-GPx (p<0.05) values while the difference was not significant for NO2-/NO3-, CAT, Zn, and Cu values. The same values were also investigated in cord blood,and only NO2/NO3-(p<0.01), Se-GPx (p<0.01 and CAT (p<0.001) values were found statistically different.Smoking mothers may have been exposed to more oxidative stress than non-smoking mothers

Association between gene polymorphism of manganese superoxide dismutase and prostate cancer risk.

Manganese superoxide dismutase (MnSOD) is the most effective antioxidant enzyme in mitochondria and protects cells from reactive oxygen species-induced oxidative damage. The aim of this study was to investigate the association between MnSOD Ala-9 Val gene polymorphism and prostate cancer (PCa) risk in Turkish men with prostate cancer. 33 patients with PCa and 81 control individuals were included in the study. We observed an association between MnSOD Ala/Ala frequency and a higher PCa risk. In addition, we found that the increased risk of early-onset PCa (under age of 65) in the men homozygous for Ala allele was higher than the men homozygous for Val allele. However, we determined that MnSOD Ala-9 Val genotype was not associated with the aggressiveness of the disease. The results of our study suggest that MnSOD Ala/Ala genotype may influence on early-onset of PCa patients, but no effect on subsequent development of the disease in Turkish men. However, our study has a limitation that is small numbers of individuals for cases and controls. Therefore, the presented study limited our statistical power to fully investigate the gene polymorphism on cancer risk.

Oxidative stress in obese children and its relation with insulin resistance.

BACKGROUND: In obese populations, oxidative stress plays a major role in the pathogenesis of serious diseases such as diabetes, coronary heart disease, and atherosclerosis. In this study, we investigated the status of oxidative stress in obese children as to nitrite/nitrate and glutathione peroxidase levels, and their relation with insulin resistance (IR). METHODS: A total of 63 obese children were enrolled in the study. Each was relegated to one of three groups: 20 obese children without IR (11 adolescents, 9 prepubertal; mean age 10.27 +/- 2.36 years; 10 males, 10 females), 22 obese children with IR (13 adolescents, 9 prepubertal; mean age 11.26 +/- 2.52 years; 10 males, 12 females), and a control group of 21 children (14 adolescents, 7 prepubertal; mean age 11.41 +/- 2.00 years; 10 males, 11 females). RESULTS: Glutathione peroxidase levels were lower in the obese group with IR than in either the control group or the obese group without IR (0.032 +/- 0.01 vs. 0.048 +/- 0.01 and 0.042 +/- 0.01, respectively). Nitrite/nitrate levels were higher in the obese group with IR than in the control group or the obese group without IR (89.83 +/- 25.00 vs. 66.00 +/- 21.75, and 68.65 +/- 28.98, respectively) and compared by pubertal status, adolescents' results were similar. However, in prepubertal children, nitrite/nitrate and glutathione peroxidase levels were not significantly different between groups. Multiple regression analysis revealed that nitrite/nitrate levels were positively correlated with the homeostasis model assessment of IR (HOMA-IR) independent of body mass index, age, gender, serum lipids, and pubertal stages, and that glutathione peroxidase levels were negatively correlated with body mass index and HOMA-IR independent of age, gender, pubertal status, and serum lipids. CONCLUSION: This study demonstrates that oxidative stress exists even in populations of obese children, and that oxidative stress markers have a relation with the HOMA-IR, which was used as a surrogate marker of IR.

Induced antioxidant activity in hospital staff occupationally exposed to ionizing radiation.

PURPOSE: Occupational exposure to low levels of ionizing radiation (IR) in radiology department staff may affect their antioxidant status. The aim of this study was to evaluate the oxidative stress parameters in radiology staff that are occupationally exposed to IR in a hospital setting. MATERIALS AND METHODS: The study population included 40 exposed radiology staff and 30 control subjects. The radiation doses of exposed staff ranged between 0.10 and 3.8 milligray (mGy) per month. The subjects' antioxidant status was determined by measuring the activities of copper zinc-superoxide dismutase (CuZn-SOD), selenium dependent glutathione peroxidase (Se-GPx), catalase (CAT) enzymes, and the levels of malondialdehyde (MDA) in erythrocytes. RESULTS: Our results showed that the activities of erythrocyte CuZn-SOD and Se-GPx enzymes observed for the radiation exposed group were significantly higher than in the controls. The activity of CAT enzyme and MDA levels were significantly lower in the exposed group than in the controls. Moreover, we investigated the influence of confounding factors on antioxidant enzymes or lipid peroxidation (LP), but we could not find any associations between them. CONCLUSIONS: Our study indicates the presence of stimulant effect of chronic low-dose radiation in exposed individuals, resulting in enhanced resistance to oxidative stress.

Evaluation of genotoxic and oxidative effects in workers exposed to jet propulsion fuel.

PURPOSE: Jet fuel is a common occupational exposure risk among military and civilian populations. The purpose of this study was to evaluate genotoxic and oxidative effects in workers occupational exposure to jet propulsion fuel (JP-8). METHODS: In this study, sister-chromatid exchange (SCE), high frequency of SCE cells (HFCs), and micronuclei (MN) were determined for 43 workers exposed to JP-8 and 38 control subjects. We measured the antioxidant enzyme activities including that of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). The levels of thiobarbituric acid-reactive substances (TBARS) were also studied. Urinary 1- and 2-naphthol excretion was used as a biomarker of occupational exposure to JP-8. RESULTS: The results obtained from cytogenetic analysis show a statistically significant increase in frequency of SCE in the exposed workers when compared to controls (P < 0.05). Interestingly, the mean value of the frequency (%o) of MN and HFCs for workers and controls did not show any statistical differences (P > 0.05). Oxidative stress parameters were not statistically different between exposed and control groups except for TBARS levels. CONCLUSION: Urinary 1-and 2-naphthol levels of exposed workers were found to be significantly higher than those of control subjects. Occupational exposure to JP-8 resulted in no significant genotoxic and oxidative effects, while smoking is the principal confounding factor for the some parameters. To understand the genotoxic and oxidative effects of JP-8 exposure, further studies should be planned to find out whether human populations may be at increased risk for cancer because of the exposures related to occupation and lifestyle.

Oxidative and antioxidative effects of desflurane and sevoflurane on rat tissue in vivo.

General anaesthetics are often used in patients who are under oxidative stress due to a critical illness or surgical trauma. Some anaesthetics may worsen oxidative stress and some may act as antioxidants. The aim of this study was to evaluate liver, brain, kidney, and lung tissue oxidative stress in rats exposed to desflurane and sevoflurane and in unexposed rats. The animals were divided in three groups: control (received only air); sevoflurane (8 %), and desflurane (4 %). After four hours of exposure, we evaluated the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), Cu, and Zn. Exposure to either of the anaesthetics significantly increased lung MDA levels compared to control (Mann-Whitney U test; P<0.05), probably because it is the tissue directly exposed to anaesthetic gases. Oxidative stress and antioxidant activity in other tissues varied between the desflurane and sevoflurane groups. Our results suggest that anaesthesiologist should not only be aware of the oxidative or antioxidative potential of anaesthetics they use, but should also base their choices on organs which are the most affected by their oxidative action.

Cytogenetic analysis of peripheral blood lymphocytes of hospital staff occupationally exposed to low doses of ionizing radiation.

Ionizing radiation is known to induce mutations and cell transformations, predominantly by causing single-strand and double-strand DNA breakage, thereby leading to chromosome instability and carcinogenesis. The aim of this study was to evaluate genotoxic effects in hospital staff exposed to low-dose ionizing radiation in comparison with a selected control group, by using the cytokinesis-blocked micronucleus (CBMN) and sister chromatid exchange (SCE) tests in peripheral blood lymphocytes. The study included 40 exposed radiology staff and 30 control subjects. The frequency of micronuclei (MN) was significantly increased in radiation-exposed groups compared with control persons (p < 0.05). The frequency of SCE did not show any significant difference in the exposed individuals in comparison to the controls. Our results showed that low-level chronic occupational exposure to ionizing radiation causes an increase of MN frequency in chromosomes, even though the absorbed doses were below the permissible limits. Our studies indicate that the CBMN assay is considered to be sensitive test in contrast to SCE analysis to evaluate chromosomal damage induced by ionizing radiation.

Proanthocyanidin to prevent formation of the reexpansion pulmonary edema.

BACKGROUND: We aimed to investigate the preventive effect of Proanthocyanidine (PC) in the prevention of RPE formation. METHODS: Subjects were divided into four groups each containing 10 rats. In the Control Group (CG): RPE wasn't performed. Then subjects were followed up for three days and they were sacrificed after the follow up period. Samplings were made from tissues for measurement of biochemical and histopathologic parameters. In the Second Group (PCG): The same protocol as CG was applied, except the administration of PC to the subjects. In the third RPE Group (RPEG): Again the same protocol as CG was applied, but as a difference, RPE was performed. In the Treatment Group (TG): The same protocol as RPEG was applied except the administration of PC to the subjects. RESULTS: In RPEG group, the most important histopathological finding was severe pulmonary edema with alveolar damage and acute inflammatory cells. These findings were less in the TG group. RPE caused increased MDA levels, and decreased GPx, SOD and CAT activity significantly in lung tissue. CONCLUSION: PC decreased MDA levels. Oxidative stress plays an important role in pathophysiology of RPE and PC treatment was shown to be useful to prevent formation of RPE.

Does the 3-aminobenzamide effect on bacterial translocation affect experimental acute necrotizing pancreatitis?

BACKGROUND/AIMS: One of the most important complications of acute pancreatitis is the secondary bacterial infections of the pancreas and gut. Translocation of bacteria from the gut is accepted as being responsible for the development of septic complications in acute pancreatitis. In this study, our aim was to investigate the effect of PARP inhibition via 3-aminobenzamide on the bacterial translocation in acute pancreatitis. METHODS: 45 male Sprague-Dawley rats were randomly allocated into three groups. Group I (Sham+saline) received normal saline infusion into the common biliopancreatic duct. Acute pancreatitis was induced in Group II (acute pancreatitis+saline) and Group III (acute pancreatitis+ 3-aminobenzamide) by the retrograde injection of taurocholate into the common biliopancreatic duct. Six hours after induction of pancreatitis, the rats in Group I and II were treated with saline (1 ml, every 12 hours), while the rats in Group III were treated with 3-aminobenzamide (10 mg/kg/day every 12 hours), intraperitoneally. In the 54th hour of the study, blood and tissue samples were taken for biochemical, microbiological and histopathological analysis. RESULTS: Acute pancreatitis developed in Groups II and III. Pathologic score [median (25-75% percentiles)] of the pancreatitis in Group III [8 (7-9)] was significantly lower than in Group II [19 (18-21)] (p<0.001). Bacterial translocation to mesenteric lymph node (53.3%), peritoneum (60%) and pancreas (46.7%) in Group III was significantly lower than in Group II (100% for all) (p<0.02, p<0.03, p<0.005, respectively). Pancreatic tissue glutathione peroxidase, superoxide dismutase, and malondialdehyde levels were better in Group III compared to Group II (p<0.001 for all). Comparison of Groups II and III demonstrated reduced severity of inflammation of the gut in Group III (p>0.05). Improvement in bacterial translocation was correlated with reducing oxidative stress. CONCLUSIONS: We demonstrated that 3-aminobenzamide therapy improved histopathologic score and oxidative stress in experimental pancreatitis. In addition, it was demonstrated microbiologically and histopathologically that 3-aminobenzamide therapy improves bacterial translocation. Further survival studies demonstrating the efficacy of 3-aminobenzamide therapy and explaining the potential mechanisms of bacterial translocation prevention in acute necrotizing pancreatitis will be beneficial.

Could rice be used as an anticaking agent in table salt?

The aim of the study was to examine whether powdered rice could be used as an anticaking agent in table salt. Salts free from anticaking food additives were selected and powdered rice was added at different concentrations (0%, 1%, 2%, 5%, 10% and 20%). The samples were placed away from direct light and airflow, and left exposed in the laboratory at room temperature and below 30% humidity. The weight of the samples was measured using an electronic laboratory balance and recorded daily for 4 days. At the end of the experiment, all the samples were dried at 105 °C in order to determine exact dryness. All the salt samples containing powdered rice lost weight (0.56±0.08%), while the other salt samples free of powdered rice gained weight (10.31±0.63%) (P<0.001). A statistically significant difference was found between the first two (1% and 2%) and last three concentrations (5%, 10% and 20%) (P<0.001). Adding powdered rice to salt as an anticaking agent during salt manufacturing at a concentration of 1% could take the place of other anticaking food additives used in table salt production.

Initial experience with silver-impregnated polyurethane ventricular catheter for shunting of cerebrospinal fluid in patients with infected hydrocephalus.

OBJECTIVE: Infection is a major complication and risk factor of cerebrospinal fluid (CSF) shunting procedures. Recently, antibiotic-impregnated shunt systems have been developed in an attempt to prevent or reduce the CSF infection. The aim of this study was to determine the efficacy of silver-impregnated polyurethane ventricular catheter for shunting of CSF in patients with infected hydrocephalus. METHODS: Seven patients who had hydrocephalus with high protein level and positive CSF culture underwent implantation of ventriculoperitoneal shunt with silver-impregnated polyurethane ventricular catheter. All of them experienced shunt failure previously due to infection. The Silverline ventricular catheter, which was connected to the Miethke gravity-assisted valve system and peritoneal catheter, was used in all patients. The mean follow-up period after operation was 14 months. Cerebrospinal fluid samples from the reservoir of the shunts were obtained at the end of the third month after operation in all patients. RESULTS: The CSF protein level of the patients was reduced significantly, and the CSF culture became negative after shunt placement with silver-impregnated polyurethane ventricular catheters. The mean CSF silver (Ag) level was 0.51 ng/ml [parts per billion (ppb)], and blood Ag level was 3.65 ng/ml (ppb) at the first month after operation. No shunt obstruction or infection was observed in the follow-up period. CONCLUSION: Silver-impregnated polyurethane ventricular catheters appear to be safe and well tolerated in patients who sustained infected hydrocephalus. Preliminary results suggest a complete improvement of infection. Longer follow-up and large number of patients are needed to more accurately assess the efficacy of these catheters.