Insulin resistance in nondiabetic chronic kidney disease patients.

Chronic kidney disease (CKD) is accompanied by numerous metabolic derangements due to risk factors such as oxidative stress, chronic inflammation, and endothelial dysfunction. Insulin resistance (IR) has been reported as an independent risk factor for cardiovascular morbidity and mortality in patients with CKD. As reported from previous studies, it has been shown that IR is also seen in mild-to-moderate stages of CKD. Hence, the present study aimed to study IR in nondiabetic CKD patients and correlated with different stages of CKD. A two-year cross-sectional study was conducted in 175 patients among whom 25 healthy controls and 150 nondiabetic CKD patients in different stages are included. In the present study, fasting insulin and homeostatic model assessment for IR (HOMA-IR) levels were found to be higher in all nondiabetic CKD patients when compared to controls which was found to be statistically significant (P <0.05). In the present study, IR, as evidenced by HOMA-IR, is noted in patients on predialysis, continuous ambulatory peritoneal dialysis (CAPD), and postrenal transplant patients. Hence, periodic monitoring of IR by HOMA-IR might be prudent in CKD patients on predialysis, CAPD and in postrenal transplant patients. Interventions targeting IR in this patient population can also decrease cardiovascular morbidity and mortality.

A Cyclic Phosphoramidate Prodrug of 2'-Deoxy-2'-Fluoro-2'-C-Methylguanosine for the Treatment of Dengue Virus Infection.

Monophosphate prodrug analogs of 2'-deoxy-2'-fluoro-2'-C-methylguanosine have been reported as potent inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase. These prodrugs also display potent anti-dengue virus activities in cellular assays although their prodrug moieties were designed to produce high levels of triphosphate in the liver. Since peripheral blood mononuclear cells (PBMCs) are among the major targets of dengue virus, different prodrug moieties were designed to effectively deliver 2'-deoxy-2'-fluoro-2'-C-methylguanosine monophosphate prodrugs and their corresponding triphosphates into PBMCs after oral administration. We identified a cyclic phosphoramidate, prodrug 17, demonstrating well-balanced anti-dengue virus cellular activity and in vitro stability profiles. We further determined the PBMC concentration of active triphosphate needed to inhibit virus replication by 50% (TP50). Compound 17 was assessed in an AG129 mouse model and demonstrated 1.6- and 2.2-log viremia reductions at 100 and 300 mg/kg twice a day (BID), respectively. At 100 mg/kg BID, the terminal triphosphate concentration in PBMCs exceeded the TP50 value, demonstrating TP50 as the target exposure for efficacy. In dogs, oral administration of compound 17 resulted in high PBMC triphosphate levels, exceeding the TP50 at 10 mg/kg. Unfortunately, 2-week dog toxicity studies at 30, 100, and 300 mg/kg/day showed that "no observed adverse effect level" (NOAEL) could not be achieved due to pulmonary inflammation and hemorrhage. The preclinical safety results suspended further development of compound 17. Nevertheless, present work has proven the concept that an efficacious monophosphate nucleoside prodrug could be developed for the potential treatment of dengue virus infection.

Serum tumor markers in advanced stages of chronic kidney diseases.

Chronic kidney disease (CKD) is one of the most important noncommunicable diseases. Abnormal concentration of some tumor markers were found in a spectrum of nonmalignant diseases such as benign ovarian tumors, breast diseases, chronic hepatitis, cirrhosis, diseases of the bile duct, and in CKD. Hence, the present study was undertaken to evaluate carbohydrate antigen (CA) 15-3, carcinoembryonic antigen (CEA), CA 19-9, and human chorionic gonadotropin (HCG) concentrations in advanced stages of CKD (Stage 4 and 5) patients who are not on dialysis and with no known malignancy. Patients included 40 CKD patients and 40 healthy controls. CA 15-3, CEA, CA 19-9, and HCG in serum were estimated by enzyme-linked immunosorbent assay method. The differences in tumor marker levels between the controls and advanced stages of CKD (Stage 4 and 5) were assessed using one-way analysis of variance using the Statistical Package for the Social Sciences for Windows version 16.5. CKD patients had significantly elevated levels of CEA, HCG, CA 19-9, and CA 15-3 compared to the control group (P = 0.001). There was no difference in the tumor markers levels between CKD Stage 4 and 5. Elevation in serum tumor markers may be a possibility in patients with CKD even in the situations of the absence of a malignancy. This may be due to an alteration in their metabolism in CKD and reduction of glomerular filtration rate leading to impaired excretion. Hence, it may be prudent to exercise caution in the interpretation of serum tumor markers as a representative for underlined malignancy in patients of CKD.

Study of contrast-induced oxidative stress in nondiabetic patients undergoing coronary angiography.

Administration of iodinated contrast media is associated with serious complications such as acute kidney injury (AKI). Oxidative stress is implicated as a major mechanism underlying the production of contrast-induced AKI (CI-AKI). There are very few human studies on oxidative stress occurring after contrast administration. Twenty-seven patients scheduled for coronary angiography were recruited. An average of 22.2 mL low-osmolal nonionic contrast was administered. Plasma conjugated dienes (CD), lipid hydroperoxides (LOOH), malondialdehyde (MDA), protein carbonyl (PC), protein thiols (PTs), ferric reducing ability of plasma (FRAP), erythrocyte super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase were estimated before, 30 min, 2 and 4 h after contrast administration. CD, LOOH, MDA, and PC increased (P <0.001), whereas PTs, FRAP, SOD, CAT (P <0.001), and GPx (P = 0.013) decreased in the first 4 h. Estimated glomerular filtration rate (eGFR) showed inverse association with MDA and positive association with GPx. The study provides evidence for oxidative stress following contrast administration even in the absence of predisposing factors. Association of eGFR with MDA and GPx indicate kidney as the source of oxidative stress. Hence, antioxidant therapy before contrast administration helps to prevent the development of oxidative stress, thereby reducing the risk of CI-AKI.

Changes in the inflammatory and oxidative stress markers during a single hemodialysis session in patients with chronic kidney disease.

BACKGROUND: Cardiovascular disease (CVD) is a common cause of morbidity and mortality in end-stage renal disease (ESRD) patients on hemodialysis (HD) among whom it is 5-20 times higher than in the general population. Some of the nontraditional risk factors such as oxidative stress and inflammation are related to the progress of CVD in HD patients. Several, but not all studies, reported that inflammatory and oxidative stress markers are increased during a single session of HD, mimicking changes that occur during acute immune activation. This study was taken up to evaluate the changes in the inflammatory and oxidative stress markers during a single HD session in patients with chronic kidney disease. METHODS: Twenty-five ESRD patients on maintenance HD and 25 controls were included in the study. Blood samples were obtained from the patients before starting of hemodialysis (pre-HD) and after completion of hemodialysis (post-HD). The changes in serum Pentraxin-3, hs-CRP, malondialdehyde (MDA) and ferric reducing ability of plasma (FRAP) levels were measured in pre- and post-HD ESRD patients and compared with healthy control group. RESULTS: This study found increased levels of Pentraxin-3, hs-CRP, MDA, and decreased level of FRAP in HD patients compared to controls. CONCLUSIONS: Hemodialysis procedure contributes to inflammation and oxidative stress.

Risk Factors for Cardiovascular Disease in Obese Children.

OBJECTIVE: To study the prevalence of cardiovascular risk factors in pediatric obesity. METHODS: 50 obese children (age 5-17y) and 50 apparently healthy non-obese children (body mass index of over 95th percentile and between 5th to 95th percentiles, respectively) using Centre for Disease Control growth charts were included. Fasting blood sugar, lipid profile, insulin, homeostasis model assessment of insulin resistance, uric acid, fibrinogen, lipoprotein (a), homocysteine, malondialdehyde, ferric reducing ability of plasma and nitric oxide were measured. RESULTS: Insulin, insulin resistance, triglycerides, uric acid, fibrinogen, malondialdehyde, ferric reducing ability of plasma and nitric oxide were significantly higher (P <0.001) in obese children. Body mass index showed significant positive correlation with insulin r=0.519, P<0.001; insulin resistance r =0.479, P<0.001; uric acid r= 0.289, P=0.005; fibrinogen r=0.461, P<0.001; and nitric oxide r=0.235, P=0.012. CONCLUSION: Pediatric obesity is associated with dyslipidemia, oxidative stress, insulin resistance and endothelial dysfunction, which are cardiovascular risk factors and components of metabolic syndrome. These children must be targeted for lifestyle and dietary modification.

Evaluation of Brown Midrib Sorghum Mutants as a Potential Biomass Feedstock for 2,3-Butanediol Biosynthesis.

Three sorghum backgrounds [Atlas, Early Hegari (EH), and Kansas Collier (KC)] and two bmr mutants (bmr6 and bmr12) of each line were evaluated and compared for grain and biomass yield, biomass composition, and 2,3-butanediol production from biomass. The data showed that the bmr6 mutation in EH background led to a significant decrease in stover yield and increase in grain yield, whereas the stover yield was increased by 64% without affecting grain yield in KC background. The bmr mutants had 10 to 25% and 2 to 9% less lignin and structural carbohydrate contents, respectively, and 24 to 93% more non-structural sugars than their parents in all sorghum lines, except EH bmr12. The total fermentable sugars released were 22 to 36% more in bmr mutants than in parents for Atlas and KC, but not for EH. The bmr6 mutation in KC background produced the most promising feedstock, among the evaluated bmr mutants, for 2,3-butanediol production without affecting grain yield, followed by KC bmr12 and Atlas bmr6, but the bmr mutation had an adverse effect in EH background. This indicated that the genetic background of the parent line and type of bmr mutation significantly affect the biomass quality as a feedstock for biochemical production.

Choroidal thickness profile in Retinitis Pigmentosa - Correlation with outer retinal structures.

PURPOSE: To compare the choroidal thickness (CT) of subjects with Retinitis Pigmentosa (RP) with age-matched healthy subjects and to correlate the visual acuity with retinal parameters including central macular thickness (CMT), inner segment/outer segment junction (IS/OS junction) integrity, external limiting membrane (ELM) integrity and choroidal thickness in subjects with RP. METHODS: Eighty-eight eyes (69 patients) with typical RP and 188 eyes of 104 healthy subjects were enrolled between September 2012 and January 2013. All subjects underwent a comprehensive ocular examination including choroidal imaging using enhanced depth imaging with spectral domain optical coherence tomography. Outcome measures were CT difference between RP and age-matched healthy subjects; and correlation of various factors such CMT, IS/OS junction integrity, ELM integrity, and CT with visual acuity. RESULTS: Among RP subjects, mean age was 31.39 ± 13.4 years with a mean BCVA of 0.99 ± 0.94 logMAR. Mean spherical equivalent was -0.6 ± 1.6D. Mean CMT was 148.48 ± 119 µm. Mean subfoveal CT was 296.9 ± 72 µm. Mean IS/OS and ELM integrity was 42.2 ± 46.6% and 43.75 ± 45.7%, respectively. The mean age was 40.0 ± 13.5 years with a mean spherical equivalent of 0.18 ± 0.6D for the normal age-matched healthy group. Mean subfoveal CT was 283.1 ± 47.8 µm. CT at various locations in patients of various ages in the RP group did not show any statistical significant difference (P = â‰«0.05) in comparison with age-matched healthy subjects. On multivariate regression, ELM percentage integrity had the strongest association with best corrected visual acuity, followed by IS/OS junction percentage integrity. Subfoveal choroidal thickness had very weak correlation with visual acuity as well other retinal parameters. There was a significant difference in the outer retinal structure integrity (p = 0.002) and CMT (p = 0.02) between the eyes with good (⩾20/200) and poor vision (<20/200), but not in subfoveal choroidal thickness (p = 0.3). CONCLUSIONS: Our study results did not show any significant difference in choroidal thickness between subjects with RP and age-matched healthy subjects. Choroidal thickness correlated better with the age but not with the vision or outer retinal structures in eyes with RP. Outer retinal structure integrity and CMT had a better correlation with visual acuity.

Effect of high pressure and thermal processing on quality changes of aloe vera-litchi mixed beverage (ALMB) during storage.

The effect of high pressure processing (HPP) (600 MPa/15 min/56 °C) and thermal processing (TP) (95 °C/5 min) on the quality characteristics of aloe vera-litchi mixed beverage samples (ALMB) stored at 4, 15 and 25 °C were studied. The total color difference and browning index of ALMB samples increased with the storage period for both HPP and TP treated samples under all storage conditions. HPP of ALMB resulted in inactivation of pectinmethylesterase (PME), polyphenoloxidase (PPO) and peroxidase (POD) to 34, 65 and 62 %, respectively after immediate processing, whereas, TP treatment lead to 83, 79 and 78 %, respectively. The residual activity of all the studied enzymes decreased with storage period. The ascorbic acid loss of up to 22 % was observed after HPP treatment and up to 31 % for thermally treated samples. Minimal changes were noted for phenolics content after HPP as well as thermal processing. The natural microbiota present in samples was below the detection limit (1 log CFU/mL) throughout the storage period. The shelf life of HPP and TP treated samples stored at 4 °C was estimated to be 100 and 80 days, respectively, based on the sensory quality, ascorbic acid degradation and instrumental color difference.

Ischemia-modified albumin levels in overt and subclinical hypothyroidism.

BACKGROUND: Free radical-mediated oxidative stress (OS) has been implicated in the pathogenesis of thyroid disorders. The ischemia-modified albumin (IMA) has been proposed as a marker of protein oxidative damage, which has been found to reflect hypoxic stress. AIM: Our aim was to evaluate IMA, malondialdehyde (MDA), and reduced glutathione (GSH) levels in patients with overt hypothyroidism (OHT) and subclinical hypothyroidism (SHT) in comparison to euthyroid controls. SUBJECTS AND METHODS: Albumin, IMA, IMA/albumin ratio, MDA, GSH, total cholesterol (TC), triglycerides (TG), HDL-Cholesterol were assessed in 105 subjects grouped into OHT, SHT patients, and euthyroid controls with 35 subjects in each group. RESULTS: MDA and IMA levels were significantly elevated while the GSH concentrations were significantly lower in OHT and SHT patients compared to controls (p < 0.01). When IMA values were normalized for albumin concentrations, the IMA/albumin ratio was also significantly elevated in both patient groups compared to controls (p < 0.01). These changes were more pronounced in the OHT group when compared to SHT group. In OHT group, thyroid-stimulating hormone (TSH) levels showed significant positive correlation with MDA (r = 0.470, p = 0.004), IMA (r = 0.530, p = 0.001), and IMA/albumin ratio (r = 0.525, p = 0.001). Both IMA (r = -0.342, p = 0.041), IMA/albumin ratio (r = -0.378, p = 0.023) showed significant negative correlation with GSH in OHT patients. No significant correlation between variables was, however, observed in SHT group. CONCLUSIONS: Increase of MDA and IMA levels with decreased antioxidant status indicate the presence of OS in hypothyroid patients, which was more pronounced in OHT patients. Elevated levels of IMA can be a clinically useful marker of protein oxidative damage and OS in hypothyroidism.

Antioxidant defense in overt and subclinical hypothyroidism.

Oxidative stress as a result of disequilibrium between free radical generation and antioxidant status has been implicated in several pathologies including thyroid diseases. Studies on antioxidant status in overt (OHT) and subclinical hypothyroidism (SHT) are controversial and limited. The aim of this study was to determine the effect of OHT and SHT on antioxidant status. Thirty-six patients with OHT, 36 patients with SHT, and 39 healthy euthyroid subjects as the control group were included in the study. Plasma levels of malondialdehyde (MDA), reduced glutathione (GSH) and total antioxidant capacity (TAC) as ferric reducing ability of plasma (FRAP), and erythrocyte antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), SOD/GPx ratios, catalase (CAT), and glutathione reductase (GR) were analyzed in all groups. MDA and GPx values were elevated, while GSH, FRAP, SOD, and SOD/GPx ratio were decreased in both patient groups compared with controls. No change in activities of CAT and GR were observed in both the patient groups. Significant differences were observed between OHT and SHT groups with high MDA, GPX and low GSH, FRAP, SOD, and SOD/GPx ratio in OHT group. Thus, hypothyroid patients have a deficient antioxidant defense in the form of decreased activity of SOD, decreased levels of FRAP and GSH along with an increase in GPx activity. The severity of the disease appears to decide the degree of deficiency and our findings also point to this, in the form of decrease in SOD, FRAP, and GSH observed being more in OHT than in SHT patients. Hormonal changes and increased lipid peroxidation, which also vary with severity of disease, appear to contribute to the antioxidant deficiency.

Lipid abnormalities, lipoprotein (a) and apoprotein pattern in non-dialyzed patients with chronic kidney disease.

The present study was carried out to explore the altered lipid, lipoprotein and apoprotein abnormalities along with lipoprotein (a) in chronic kidney disease patients with stage I to V which were further divided into group 1 (stage I and II), group 2 (stage III and IV) and group 3 (stage V). 50 chronic kidney disease patients with stage I to V and 20 healthy normal subjects as controls were recruited for this study. Among the various parameters tested triglyceride levels were high in group 1 and 2, whereas VLDL cholesterol, Lp (a) and apo B levels were significantly high in all the groups when compared to controls (P<0.05). However, LDL cholesterol level was significantly low in group 3 only as compared to control group (P<0.05). Apoprotein AI values also showed significant decrease in all groups as compared to controls (P<0.05). Though total cholesterol levels in group 1 and LDL levels in group 1 and 2 were higher than controls, but the values attained not statistically significant (P>0.05). In conclusion high levels of VLDL cholesterol, Lp (a), apo B and low levels of apoprotein AI as reported in this study are the major lipid disorders in the development of cardiovascular complications at all the stages in these patients.

Carotid intima-media thickness in patients with end-stage renal disease.

Accelerated atherosclerosis and cardiovascular disease are major causes of morbidity and mortality in patients of end-stage renal disease. Carotid intima media thickness is taken as a useful surrogate marker of atherosclerosis. Thirty end-stage renal disease (ESRD) patients were subjected to ultrasonography to study CIMT before the initiation of dialysis. CIMT was found to be higher in ESRD patients than in controls. Levels of a serum marker of oxidative stress were also found to be higher in patients than in the controls. CIMT is an easy, noninvasive, reproducible, and cost-effective investigation in patients with chronic renal failure.

Association of serum antioxidants and risk of coronary heart disease in South Indian population.

BACKGROUND AND AIM: Higher prevalence of coronary heart disease (CHD) has been reported in south Indian population, which cannot be accounted for by the traditional risk factors like hyperlipidemia. Identification of new risk factors may help in treatment and prevention of CHD in this part of the world. In an attempt to investigate the causes of increased incidence of CHD in this part of the world, we intended to look for oxidative stress in our patients as a possible risk factor. As an initial step in this perspective, a case- control study was conducted to find out the serum antioxidant levels and their association with CHD in south Indian population. SETTINGS AND DESIGN: A tertiary care hospital; Case--control study. MATERIALS AND METHODS: One hundred thirty nine angiographically proven CHD patients (aged 29-75 years) were studied against 59 population based healthy controls (aged 29-72 years) free of CHD. Fasting serum cholesterol, triglycerides, HDL cholesterol, erythrocyte and plasma glutathione peroxidase and superoxide dismutase were estimated on automated clinical chemistry analyzer. LDL cholesterol and VLDL cholesterol were calculated. Vitamins A and E were estimated using high performance liquid chromatography (HPLC). STATISTICAL ANALYSIS: Unpaired t test was used to compare means. Binary logistic regression was done to find out the association between dependent and independent variables. RESULTS: Significantly higher levels of Total Cholesterol/HDL cholesterol and LDL cholesterol/HDL cholesterol ratio and lower HDL cholesterol levels were observed in patients when compared to controls. No significant difference of plasma and erythrocyte glutathione peroxidase and superoxide dismutase activity was observed between patients and controls. Significantly lower levels of vitamin E in patients than in controls was observed (P<0.001). Serum vitamin E was inversely associated with coronary heart disease even after controlling for age and other coronary risk factors (Odds ratio 0.898, 95% CI 0.826-0.976 P=0.01). CONCLUSIONS: The results of present study suggest that deficiency of vitamin E may be an independent risk factor of CHD. This study brings out the need for long- term monitoring of vitamin E supplementation as a preventive measure for CHD in the population studied.

Removal of nickel (II) from aqueous solutions using marine macroalgae as the sorbing biomass.

In the present study biosorption technique, the passive accumulation of metals by biomass, is used for the removal of nickel from aqueous medium. The brown algae, Sargassum sp., in its natural and acid treated forms are used as a low cost sorbent. The adsorption characteristics of nickel on Sargassum sp. are evaluated as a function of time, pH, adsorbent dosage and initial concentration of nickel. The equilibrium adsorption data are fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters are evaluated. Both the models represent the experimental data satisfactorily. The adsorption follows Lagergren first order kinetic model. The monolayer adsorption capacities of natural and acid treated forms of algae as obtained from Langmuir adsorption model are found to be 181 and 250mg g(-1) respectively.

Lipoprotein (A): Better assessor of coronary heart disease risk in south Indian population.

In an attempt to search for risk factors which can explain the increasing prevalence of coronary heart disease (CHD) in Indian population, we conducted a case-control study to assess the association of Lipoprotein (a)(Lp(a)) with CHD. One hundred and fifty one consecutive patients with clinical and angiographic evidence of CHD and forty-nine healthy controls were drawn for the study. Triglycerides, very low density cholesterol (VLDL-C), total cholesterol (total-C)/high density cholesterol (HDL-C) ratio, low density cholesterol (LDL-C)/HDL cholesterol ratio and Lp(a) were found to be higher in patients than controls. In female sex and in those with family history of CHD, higher total and LDL cholesterol levels were observed to be associated with higher Lp(a) levels. Lp(a) levels were also found to be higher in triple vessel disease than other vessel disease patients. Significant difference in Lp(a) levels were observed between normal coronaries vs. single and triple vessel disease(P<0.05) and also between single vs. double and triple vessel disease (P<0.01).Lp(a) levels correlated positively with vessel severity(P<0.005). Lp(a) levels >25 mg/dl were associated with coronary heart disease (Odds ratio 1.98 P<0.05 95% CI 0.007-1.18). Our findings suggest a cut-off level of 25mg/dl for determination of risk of CHD. Studies from different areas involving larger sample size are needed to confirm the findings of the present study.

A major catalase (KatB) that is required for resistance to H2O2 and phagocyte-mediated killing in Edwardsiella tarda.

Edwardsiella tarda causes haemorrhagic septicaemia in fish and gastro- and extra-intestinal infections in animals including humans. Resistance to phagocyte-mediated killing is one of the virulence factors of Ed. tarda. The authors' previous studies using TnphoA transposon mutagenesis indicated that katB mutants derived from the strain PPD130/91 are at least 1.6 log higher in LD50 values than the wild-type strain. These findings suggest the involvement of catalase (KatB) in Ed. tarda pathogenesis. In this study, experiments were conducted to characterize the contribution of KatB to Ed. tarda infection. Zymographic analyses indicated that the 22 Ed. tarda strains examined expressed three different types of catalase-peroxidases (Kat1-3) based on their mobility in non-denaturing polyacrylamide gels. KatB (Kat1), the major catalase enzyme, was expressed in eight out of 22 Ed. tarda strains, and was commonly found in virulent strains except AL9379. AL9379 has a mutated katB, which has a base substitution and a deletion that translate into stop codons in the catalase gene. KatB produced by PPD130/91 was located in both periplasmic and cytoplasmic fractions and was constitutively expressed in various growth phases. Kinetics studies indicated that the catalase provided resistance to H2O2- and phagocyte-mediated killing. Infection kinetics studies of katB mutant 34 in gourami fish demonstrated its inability to survive and replicate in phagocyte-rich organs and this prevented the dissemination of infections when compared to the wild-type. Complementation of catalase mutants restored the production of catalase, and led to an increase in the resistance to H2O2- and phagocyte-mediated killing, and a decrease in LD50 values. This study has identified and characterized a major catalase gene (katB) that is required for resistance to H2O2- and phagocyte-mediated killing in Ed. tarda. The results also suggest that catalase may play a role as a virulence factor in Ed. tarda pathogenesis.

Opsonized virulent Edwardsiella tarda strains are able to adhere to and survive and replicate within fish phagocytes but fail to stimulate reactive oxygen intermediates.

Edwardsiella tarda is responsible for hemorrhagic septicemia (edwardsiellosis) in fish and also causes diseases in higher vertebrates such as birds, reptiles, and mammals, including humans. Interactions of E. tarda with blue gourami phagocytes were studied by light microscopy as well as by adherence, intracellular replication, and superoxide anion assays. Both nonopsonized virulent (PPD130/91 and AL9379) and avirulent (PPD125/87 and PPD76/87) bacteria could adhere to and survive and replicate within phagocytes, while only opsonized virulent strains replicated within the phagocytes. Furthermore, only avirulent E. tarda elicited a higher rate of production of reactive oxygen intermediates (ROIs) by phagocytes, indicating that they were unable to avoid and/or resist reactive oxygen radical-based killing by the fish phagocytes. TnphoA transposon mutagenesis was used to construct a library of 200 alkaline phosphatase (PhoA+) fusion mutants from a total of 182,000 transconjugants derived from E. tarda PPD130/91. Five of these mutants induced more ROI production in phagocytes than the wild-type strain. Two mutants had lower replication ability inside phagocytes and moderately higher 50% lethal dose values than the wild-type strain. Sequence analysis revealed that three of these mutants had insertions at sequences having homology to PhoS, dipeptidase, and a surface polymer ligase of lipid A core proteins of other pathogens. These three independent mutations might have changed the cell surface characteristics of the bacteria, which in turn induced phagocytes to produce increased ROIs. Sequences from two other mutants had no homology to known genes, indicating that they may be novel genes for antiphagocytic killing. The present study showed that there are differences in the interactions of virulent and avirulent E. tarda organisms with fish phagocytes and PhoA+ fusion mutants that could be used successfully to identify virulence genes. The information elucidated here would help in the development of suitable strategies to combat the disease caused by E. tarda.

Oxidative stress in haemodialysis: immediate changes caused by passage of blood through the dialyser.

Oxygen free radicals have been implicated in the long-term complications of maintenance haemodialysis. Studies that have probed into the mechanisms of oxygen radical production have implicated the bio-incompatibility of dialysis membranes. Changes between the arterial (inlet) and venous (outlet) points of a dialyser may give a better picture of blood membrane interaction. There are very few studies on changes across the dialyser. Hence, it was planned to study the immediate changes that occur due to passage of blood through the dialyser. Changes between the arterial and venous ends of the dialyser after 1 h of dialysis were studied in four combinations of dialysate and membrane. There was a significant decrease in plasma vitamin E concentrations in all the groups during first-use dialysis. This was not observed with re-use dialysis. A decrease in plasma lipid peroxides was also observed in all the groups with both first and re-use dialysis. There was no significant difference in the parameters studied among the four types of dialysis. A less severe, reactive oxygen radical generation was observed with re-use of membranes.