Oxidative stress as a mechanism of chronic cadmium-induced hepatotoxicity and renal toxicity and protection by antioxidants

The role of oxidative stress in chronic cadmium (Cd) toxicity and its prevention by cotreatment with antioxidants was investigated. Adult female Sprague-Dawley rats were injected sc with 5 micromol CdCl2/kg/day, 5 times a week, for up to 22 weeks. Serum alanine amino transferase and lactate dehydrogenase activities were elevated after 9 weeks of Cd administration, indicating hepatic damage. Renal toxicity, indicated by elevation in urinary lactate dehydrogenase activity and protein, was also observed around this time. Chronic Cd administration resulted in a gradual rise in hepatic as well as renal cortex glutathione levels. In spite of this, lipid peroxidation increased in both tissues, particularly during the second half of the Cd exposure period. Depletion of glutathione following buthionine sulfoximine administration at the end of Week 5, or inhibition of catalase by aminotriazole at the end of Week 7, resulted in the development of acute nephrotoxicity within 6 h. Coadministration of antioxidants, N-acetylcysteine (50-100 mg/kg, sc), or vitamin E (100-150 mg/kg, sc) with Cd, starting from the early phases of Cd exposure, controlled Cd-induced lipid peroxidation and protected the animals against hepatic as well as renal toxicity. A Japanese hepatoprotective drug, Stronger Neo-Minophagen C, containing glycyrrhizin, glycine, and cysteine, was also effective in reducing the chronic Cd nephrotoxicity. In conclusion, oxidative stress appears to play a major role in chronic Cd-induced hepatic and renal toxicity since inhibition of components of the antioxidant defense system accelerated and administration of antioxidants protected against Cd toxicity.

Treatment of chronic cadmium nephrotoxicity by N-acetyl cysteine

Chronic cadmium (Cd)-induced nephrotoxicity is believed to be irreversible at advanced stages and no treatment is currently available. This study examined the beneficial effect of N-acetyl cysteine (NAC) on Cd-induced nephrotoxicity. Female Sprague-Dawley rats were injected s.c. with 5 micromol CdCl2/kg per day, five times/week for up to 26 weeks. Nephrotoxicity was detected after 10 weeks by elevation in urinary lactate dehydrogenase activity and protein. NAC co-administration from week 13 prevented the progression of nephrotoxicity. In these animals, with low-level nephrotoxicity, discontinuation of Cd exposure at the end of week 22 resulted in gradual recovery over the next several weeks, without the need for treatment with NAC. On the other hand, discontinuation of NAC co-treatment at the end of week 22 resulted in quick progression of nephrotoxicity, indicating that NAC protection was short-lived. Resumption of NAC treatment and cessation of Cd exposure after 26 weeks resulted in rapid recovery from advanced nephrotoxicity. It is concluded that protection from Cd-induced nephrotoxicity is possible by continued co-administration of NAC and that recovery from advanced nephrotoxicity can also be achieved with NAC, provided that Cd exposure is stopped.

Purification of a multipotent antideath activity from bovine liver and its identification as arginase: nitric oxide-independent inhibition of neuronal apoptosis

Catalase is an antioxidant enzyme that has been shown to inhibit apoptotic or necrotic neuronal death induced by hydrogen peroxide. We report the purification of a contaminating antiapoptotic activity from a commercial bovine liver catalase preparation by following its ability to inhibit apoptosis when applied extracellularly in multiple death paradigms. The antiapoptotic activity was identified by protein microsequencing as arginase, a urea cycle and nitric oxide synthase-regulating enzyme, and confirmed by demonstrating the presence of antiapoptotic activity in a >97% pure preparation of recombinant arginase. The pluripotency of recombinant arginase was demonstrated by its ability to inhibit apoptosis in multiple paradigms including rat cortical neurons induced to die by glutathione depletion and oxidative stress, by 100 nM staurosporine treatment, or by Sindbis virus infection. The protective effects of arginase in these apoptotic paradigms, in contrast to previous studies on excitotoxic neuronal necrosis, are independent of nitric oxide synthase inhibition. Rather, arginase-induced depletion of arginine leads to inhibition of protein synthesis, resulting in cell survival. Because inhibitors of nitric oxide synthesis and of protein synthesis have been shown to decrease necrotic and apoptotic death, respectively, in animal models of stroke and spinal cord injury, arginine-depleting enzymes, capable of simultaneously inhibiting protein synthesis and nitric oxide generation, may be propitious therapeutic agents for acute neurological diseases. Furthermore, our results suggest caution in attributing the cytoprotective effects of some catalase preparations to catalase.

Molecular analysis of toxigenic Vibrio cholerae O139 Bengal strains isolated in Bangladesh between 1993 and 1996: evidence for emergence of a new clone of the Bengal vibrios

Vibrio cholerae O139 Bengal emerged in 1992 and rapidly spread in an epidemic form, in which it replaced existing strains of V. cholerae O1 in Bangladesh during 1992 and 1993. The subsequent emergence of a new clone of V. cholerae O1 of the El Tor biotype that transiently displaced the O139 vibrios during 1994 to 1995 and the recent reemergence of V. cholerae O139 and its coexistence with the El Tor vibrios demonstrated temporal changes in the epidemiology of cholera in Bangladesh. We studied clonal diversity among V. cholerae O139 strains isolated from cholera patients and environmental surface water since their first appearance until their transient disappearance in 1994 as well as the O139 strains that reemerged during 1995 to 1996 and were isolated in the capital Dhaka and four rural districts of Bangladesh to investigate the origin of the reemerged strains. Analysis of restriction fragment length polymorphisms in genes for conserved rRNA and cholera toxin (CT) (ctxA) or in DNA sequences flanking these genes revealed four different ribotypes and four different ctx genotypes among the 93 strains of V. cholerae O139 studied. Ribotypes I and II and ctx genotypes A through C were shared by strains isolated from the epidemic outbreak during 1992 and 1993 in Bangladesh and India, ribotype III was represented by a single CT-negative O139 strain from Argentina, and 16 of 27 (59.2%) of the reemerged strains isolated during 1995 and 1996 belonged to a new ribotype of O139 vibrios designated ribotype IV. All 16 strains belonging to ribotype IV also belonged to a new ctx genotype (genotype 4). These results provide evidence for the emergence of a new clone of toxigenic V. cholerae O139 in Bangladesh. Further analysis of the rfb gene cluster by PCR revealed the absence of a large region of the O1-specific rfb operon and the presence of an O139-specific genomic region in all O139 strains. The PCR amplicon corresponding to the rfaD gene of a CT-negative O139 strain from Argentina was smaller in length than those of the toxigenic O139 strains but was identical to those of seven non-O1 and non-O139 strains. All O139 strains except the CT-negative strain carried structural and regulatory genes for CT and toxin-coregulated pili (ctxA, tcpA, tcpI, and toxR). These results suggest that the O139 Bengal strains possibly emerged from an El Tor strain but that the CT-negative non-Bengal O139 strain might have emerged from a non-O1, non-O139 strain. Thus, strains belonging to the O139 serogroup may have emerged from similar serotype-specific genetic changes in more than one progenitor strain of V. cholerae.

Malnutrition, cell-mediated immune deficiency and acute upper respiratory infections in rural Bangladeshi children

A community-based longitudinal study conducted in rural Bangladesh investigated the association between nutritional status, cell-mediated immune status and acute upper respiratory infections (URI). A total of 696 children aged 0-59 months was followed prospectively for 1 y yielding 183,865 child-days' observation. Trained field workers visited each child every 4th d and collected morbidity data on symptoms suggesting URI (cough, fever, nasal discharge) for the preceding 3 d by recall. On the day of visit they examined each child reporting cough and/or fever to record the temperature, presence of nasal discharge, rate of respiration and presence of chest indrawing. Anthropometry for all children was conducted monthly. Cell-mediated immune competence was assessed by a multiple antigen skin test at baseline and thereafter every 3 months. The incidence of URI was 5.3 episodes per child-year observed. Approximately three-quarters of the study children were below -2 Z-score weight for age and height for age, and a quarter below -2 Z-score weight for height. During different test periods 9-21% of the study children did not respond to any of the test antigens. In a regression model children < -2 Z-score for weight for height had 16% [odds ratio (OR) 1.16, 95% confidence interval (CI) 1.03-1.31, p = 0.01] higher risk of developing URI. Anergic children had 20% higher risk (OR 1.20, CI 1.05-1.38, p = 0.009) of URI than immunocompetent children. The study demonstrated that wasting and depressed cell-mediated immunity (CMI), but not stunting, were associated with the incidence of URI among rural Bangladeshi children.

Acute respiratory infections in children: a community-based longitudinal study in rural Bangladesh

A community-based logitudinal study conducted in Matlab, a rural area in Bangladesh, investigated acute respiratory infections (ARI) among children. A cohort of 696 children under 5 years of age was followed for 1 year yielding 183,865 child-days of observation. Trained field workers visited the study children every fourth day. Data on symptoms suggesting ARI, such as fever, cough, and nasal discharge, were collected for the preceding 3 days by recall. To determine the type and severity of ARI, the field workers conducted physical examinations (temperature, rate of respiration, and chest indrawing) of children reporting cough and/or fever. The overall incidence of ARI was 5.5 episodes per child-year observed; the prevalence was 35.4 per hundred days observed. Most of the episodes (96 per cent) were upper respiratory infections (URI). The incidence of acute lower respiratory infections (ALRI) was 0.23 per child per year. The incidence of URI was highest in 18-23-month-old children, followed by infants 6-11 months old. The highest incidence of ALRI was observed in 0-5-month-old infants followed by 12-17-month-old children. Among 559 children who were followed for 6 months or longer, about 9 per cent did not suffer any URI episode and about 16 per cent suffered one or more ALRI episodes. About 46 per cent of URI and 65 per cent of ALRI episodes lasted 15 days or more. The incidence rates of URI were higher during the monsoon and pre-winter periods, and that of ALRI at the end of the monsoon and during the pre-winter periods. Sociodemographic variables were not associated with the incidence of URI or ALRI. The study documents ARI to be a major cause of morbidity among rural Bangladeshi children.

Acute lower respiratory infections in rural Bangladeshi children: patterns of treatment and identification of barriers

A study conducted in rural Bangladesh examined the patterns of health seeking behavior, mothers' recognition of symptoms, the perceived causes and barriers to timely treatment of acute lower respiratory infections (ALRI). A total of 194 children under 5 years of age suffering from ALRI in an intensive maternal child health and family planning area was prospectively followed. About 62% of the mothers sought allopathic treatment for their children within 24 hours of case detection. No treatment of any kind was sought in 45 (23.2%) cases. Most of the mothers could recognize the different symptoms of ALRI. Cold was reported as the most common cause of ALRI. No significant difference was observed in the reported symptoms or perceived cause of the disease between those who sought no treatment and those who sought allopathic, homeopathic, spiritual or combined treatments. Failure to recognize severity followed by work loss were the most common reasons identified for not seeking any medical care. Whether or not a mother sought allopathic treatment was not associated with the child's age, sex, mother's age, mother's education, duration of illness, birth order, housing type or distance from the health center. The study indicates the potential value of giving parents clear guidelines on recognition of severity of symptoms of ALRI and motivating them to seek treatment quickly when these symptoms present. Health service providers should be aware of the heavy work loads which rural women have and the severe time constraints which deter them from seeking timely treatment from the appropriate sources.

Vibrio cholerae O139: how great is the threat of a pandemic?

The emergence of the new strain Vibrio cholerae O139 and its rapid spread in Bangladesh and India together with its detection in several other countries, have raised the question whether this constitutes the beginning of the eighth pandemic of cholera, and if so, how large a threat it poses. In an attempt to answer this question, epidemic spread patterns of Vibrio cholerae O139 strain in Bangladesh were studied. Initially the epidemic moved quickly and affected the entire coastal and estuarine tidal plains of southern Bangladesh. In the flood plains of the northern regions it affected mostly the north-eastern and north-central areas, at a slower pace than in the southern areas. In the beginning the new strain totally displaced both biotypes (classic and El Tor) of Vibrio cholerae O1. Nearly 2 years after its initial detection, striking differences in the distribution of V. cholerae O139 and O1 were observed. In most northern areas, the new strain was replaced by V. cholerae O1, whereas in the southern coastal regions, the O139 strain continues to dominate epidemics. The study suggests that the O139 strain may become endemic in the coastal ecosystem. The threat of a pandemic, therefore, may not be as large as it first seemed.

Association between nutritional status, cell-mediated immune status and acute lower respiratory infections in Bangladeshi children

OBJECTIVE

To investigate the association between nutritional status, cell-mediated immune status and the incidence of acute lower respiratory infections (ALRI).

DESIGN

Community-based longitudinal study.

SETTING

Three villages in rural Bangladesh at Matlab.

SUBJECT

696 children aged 0-59 months were followed up for a year.

METHODS

Trained field workers visited all children every fourth day and collected morbidity data for the preceding three days by recall. To determine the type and severity of respiratory infections, the field workers physically examined each child reporting a cough. Anthropometric status was determined monthly and cell-mediated immune status by skin tests was assessed at the beginning of the study and thereafter every 3 months.

RESULTS

The incidence of ALRI was 23 episodes per 100 child-years. A total of 73-78% of the children were below -2 z score weight for age, 15-30% were below - 2 z score weight for height, and 68-76% were below -2 z score height for age. In logistic regression models, malnutrition as assessed by weight-for-height status [odds ratio (OR) 0.66, 95% confidence interval (CI) 0.45-0.96, P = 0.03] or weight-for-age status (OR 0.64, 95% CI 0.45-0.92, P = 0.02) was significant predictor of ALRI. Anergic children had a higher risk of ALRI which approached to be statistically significant (OR 1.81, 95% CI 0.92-3.55, P = 0.08).

CONCLUSIONS

Improvement of nutritional and cell-mediated immune status in rural Bangladeshi children should reduce the incidence of ALRI.

Dichlone-induced oxidative stress in a model insect species, Spodoptera eridania

Southern armyworm, Spodoptera eridania, larvae were provided ad libitum 0.002-0.25% w/w dichlone, 2,3-dichloro-1,4-naphthoquinone (CNQ). Larval mortality occurred in a time-and-dose dependent manner, with an LC17 of 0.01% and an LC50 of 0.26% CNQ at day-5. Extracts of larvae fed control, 0.01, and 0.25% CNQ diets for 5 days were assayed for antioxidant enzymes. While 0.01% CNQ had a mild effect, 0.25% CNQ profoundly increased levels of all antioxidant enzymes that were examined. The increases as compared to control were: 5.3-, 1.9-, 3.2-, 2.6-, 2.8-, and 3.5-fold higher for superoxide dismutase, catalase, glutathione transferase and its peroxidase activity, glutathione reductase and DT-diaphorase, respectively. At 0.01% CNQ, the thiobarbituric acid reactive substances (TBARS) were similar to the control group. However, despite the induction from 0.25% CNQ of all enzymes examined, the lipid peroxidation was not attenuated; the TBARS were 29.7% over the control value. High mortalities and CNQ-induced pathologies reflected in retarded growth, wasting syndrome, and diuresis clearly indicated that the insect sustained severe oxidant-induced injuries before appropriate defenses were fully mobilized. Thus, this quinone causes an oxidative stress in a model insect species analogous to that observed in mammalian species.

Why treatment centres failed to prevent cholera deaths among Rwandan refugees in Goma, Zaire

In July, 1994, in one of the worst cholera outbreaks in recent times, an estimated 12,000 Rwandan refugees died in Goma in eastern Zaire. The Vibrio cholerae strains were resistant to tetracycline and doxycycline, the commonly used drugs for cholera treatment. Despite the efforts of international organisations, which provided medical relief by establishing treatment centres in Goma, mortality from the disease was much higher than expected. In the area of Muganga camp, which had the largest concentration of refugees and where most of the medical aid organisations were active, the highest reported case-fatality ratio for a single day was 48%. The slow rate of rehydration, inadequate use of oral rehydration therapy, use of inappropriate intravenous fluids, and inadequate experience of health workers in management of severe cholera are thought to be some of the factors associated with the failure to prevent so many deaths during the epidemic. In one of the temporary treatment centres with the worst case-fatality record, our team showed that improvement of these factors could increase the odds of survival of cholera patients even in a disaster setting.

An insect model for assessing oxidative stress related to arsenic toxicity

The potential usefulness of an insect model to evaluate oxidative stress induced by environmental pollutants was examined with trivalent arsenic (As3+, NaAsO2) and pentavalent arsenic (As5+, Na2HAsO4) in adult female house flies, Musca domestica, and fourth-instar cabbage loopers, Trichoplusia ni. M. domestica was highly susceptible to both forms of arsenic following 48 h exposure in the drinking water with LC50s of 0.008 and 0.011% w/v for As3+ and As5+, respectively. T. ni larvae were susceptible to dietary As3+ with an LC50 of 0.032% w/w but seem to tolerate As5+ well with an LC50 of 0.794% concentration after 48 h exposure. The minimally acute LC5 dose of both As3+ and As5+ varied considerably but averaged 0.005% for both insects. The potential of both valencies of arsenic for inducing oxidative stress in the insects exposed ad libitum to approximately LC5 levels was assessed. The parameters examined were the alterations of the antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), the peroxidase activity of glutathione transferase (GSTPX), and glutathione reductase (GR), and increases in lipid peroxidation and protein oxidation. SOD (1.3-fold), GST (1.6-fold), and GR (1.5-fold) were induced by As3+ in M. domestica but CAT and GSTPX were not affected. As5+ had no effect on M. domestica. In T. ni, the antioxidant enzyme activities were not affected by As3+ except for SOD which was suppressed by 29.4% and GST which was induced by 1.4-fold. As5+ had no effect except the suppression of SOD by 41.2%. Lipid peroxidation and protein oxidation, which represent stronger indices of oxidative stress, were elevated in both insects by up to 2.9-fold. However, based on the antioxidant enzyme response to the arsenic anions, the mode of action of arsenic induced oxidative stress may differ between the two insects. Until this aspect is further clarified, evidence at this time favors the prospect of As3+ as a pro-oxidant, especially for M. domestica.

Mitomycin C induced alterations in antioxidant enzyme levels in a model insect species, Spodoptera eridania

1. An insect species, the southern armyworm Spodoptera eridania, was used as an in vivo model to examine mitomycin C's (MMC) pro-oxidant effect reflected in alterations of antioxidant enzymes. 2. Following a 2-day exposure to 0.01 and 0.05% w/w dietary concentrations, MMC only induced superoxide dismutase activity. All other enzyme activities were not affected, indicating oxidative stress was mild. 3. Following a 5-day exposure to 0.05% w/w dietary MMC, the activities of superoxide dismutase, glutathione-S-transferase and its peroxidase activity and DT-diaphorase were induced. GR activity was not altered. The high constitutive catalase activity was also not affected. These responses of S. eridania's antioxidant enzymes are analogous to those of mammalian systems in alleviating MMC-induced oxidative stress. 4. S. eridania emerges as an appropriate non-mammalian model for initial and cost-effective screening of drug-induced oxidative stress.

Isolation of Vibrio cholerae O139 synonym Bengal from the aquatic environment in Bangladesh: implications for disease transmission

Currently, Bangladesh is experiencing an epidemic of acute watery diarrhea caused by Vibrio cholerae O139. Surface waters were collected and cultured for vibrious following enrichment. Twelve percent (11 of 92) of samples yielded V. cholerae O139, and all of them were positive for cholera toxin. The data suggest that V. cholerae O139 is easily culturable from surface water samples.

An insect model for assessing mercury toxicity: effect of mercury on antioxidant enzyme activities of the housefly (Musca domestica) and the cabbage looper moth (Trichoplusia ni)

The effect of mercury as Hg2Cl2 and HgCl2 on the antioxidant enzyme levels and its toxicity was investigated in an insect model comprised of adult females of the common housefly, Musca domestica, and fourth-instar larvae of the cabbage looper moth, Trichoplusia ni. HgCl2 was found to be more toxic than Hg2Cl2 to both M. domestica and T. ni. The LC50s for M. domestica were 1.17% and 0.38% w/v concentration for Hg2Cl2 and HgCl2, respectively. For the more tolerant T. ni, the LC50S were 5.15% for Hg2Cl2 and 0.96% w/w concentration for HgCl2. The minimally acute LC5 dose of both oxidation states of Hg was approximately 0.005% for both insects (w/v for M. domestica and w/w for T. ni). At the LC5, both forms of Hg significantly induced the activity of superoxide dismutase in both insect species. Catalase was induced by both Hg2Cl2 and HgCl2 in M. domestica but was only induced by HgCl2 in T. ni. Glutathione-S-transferase, its peroxidase activity, and glutathione reductase activities were also significantly altered in most cases by Hg in both insects although the pattern of alternation was different between the two insects. It is evident that mercury induces oxidative stress in insects as it does in vertebrates. Our findings suggest that insects may serve as a valuable, non-mammalian model species to assess Hg-induced oxidative stress as a component of environmental toxicity.

Hematological effects of aluminum on living organisms

1. Aluminum has been of great interest for many researchers over a number of years; its biochemical and physiological role is not yet fully clear. There are few papers describing the hematological consequences of its excess in living organisms and most of their data are cited in this paper. 2. Aluminum reduced the deformability of erythrocytes, and such cells are rather frequently retained in the reticuloendothelial system of the spleen and eliminated faster from the blood stream. 3. Aluminum produces peroxidative changes in the erythrocytes membrane, leading to hemolysis. Therefore, the depressed erythrocyte count in animals intoxicated with aluminum may be the consequence of both the hemolytic action of aluminum and the shortened time of survival of erythrocytes. 4. It was demonstrated that aluminum inhibits heme biosynthesis in vitro. This problem requires, however, further studies and observation. 5. Changes occurring under the influence of Al3+ on the leukocyte system of animals suggest the influence of this element on the resistance of the organism, but the mechanism of the action of Al3+ still requires elucidation. 6. Cell metabolism including blood cells may be affected by aluminum in many ways, the more so as the element may combine in vitro with amino acids, peptides, proteins, enzymes, substrates, cofactors, nucleotides and carbohydrates. Aluminum stimulates NADPH oxidation and takes part in the process of free radical formation.

Hematological and enzymatic results of aluminum intoxication in rats

1. The study has been carried out on Wistar rats. The aim of the present study was to trace the effect of aluminum on enzyme activities and hematological parameters on erythrocytes. 2. Aluminum decreased activities of acetylcholinesterase, glutathione reductase, glucose-6-phosphate dehydrogenase, and lactate dehydrogenase in the erythrocytes of the animals tested. 3. In the peripheral blood, a significant decrease in the erythrocyte count, hemoglobin level and hematocrit index and increased percentage of reticulocytes and polychromatophilic erythrocytes were observed. 4. The increase in the neutrophilic granulocyte and lymphocyte count was significant. 5. An inhibitory effect of aluminum on the phagocytic activity of granulocytes was also observed.

Inhibition of delta aminolevulinic acid dehydratase activity by aluminum

1. Studies were performed regarding the effects of aluminum chloride and aluminum nitrate in concentrations of 5 mg/kg of body weight on the delta aminolevulinic acid dehydratase activity, iron level and hematological parameters. Wistar rats were exposed to these pollutants for 10, 20, 40 and 80 days. 2. The results demonstrated that aluminum chloride was more toxic than aluminum nitrate and both treatments brought about significant changes in these parameters in Wistar rats bone marrow. 3. The toxic effects of aluminum chloride and aluminum nitrate are manifested by a significant decrease of delta aminolevulinic acid dehydratase activity in the bone marrow of rats. 4. The iron level in bone marrow with aluminum chloride and aluminum nitrate gradually dropped after 10, 20, 40 and 80 days of intoxication. 5. In the peripheral blood a significant decrease in the erythrocyte count, hemoglobin level, hematocrit value and an increase in mean corpuscular hemoglobin (MCH) were also found in experimental animals.

Lack of therapeutic efficacy of vitamin A for non-cholera, watery diarrhoea in Bangladeshi children

Vitamin A deficiency has been postulated to increase childhood mortality, possibly through increasing the severity and case-fatality of infectious diseases like diarrhoea. A clinical trial was conducted to measure the effect of vitamin A therapy on the severity and duration of acute episodes of non-cholera, watery diarrhoea; 83 children with less than 48 h of illness were randomized to receive vitamin A (200,000 IU of retinyl palmitate) orally or placebo during hospitalization at the International Centre for Diarrhoeal Disease Research in Bangladesh. The patients were similar initially with regard to age, nutritional status and severity of diarrhoea prior to admission. No adverse effects of vitamin A were detected. During hospitalization there were no differences between groups in duration of illness or stool output. Thus, vitamin A can be given safely during diarrhoeal illness to augment hepatic reserves and possibly provide a beneficial effect in regard to subsequent episodes of diarrhoea and other infections, but this supplementation should not be expected to have a therapeutic effect on a current episode.