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PubMed2002

Tumor necrosis factor-alpha and interleukin-1beta levels in recurrent and persistent otitis media with effusion.

OBJECTIVE: Based on interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha levels in effusions, our goals were to specify either recurrent or persistent otitis media with effusion (OME) is a mid stage in the development of chronic disease and to identify the factors that have an influence on cytokine levels. STUDY DESIGN: Samples from groups with recurrent (n = 15) and persistent (n = 39) OME were assayed for IL-1beta and TNF-alpha. Children were also grouped with respect to age, sex, quality of effusion, and the presence of pharyngeal adenoid tissue. SETTING: Tertiary referral center. RESULTS: In recurrent and persistent OME groups, IL-1beta was higher than TNF-alpha (P < 0.01). IL-beta was higher in recurrent OME than in persistent OME (P < 0.05). CONCLUSION: Recurrent OME seems to be closer to the chronic stage of the disease relative to persistent OME in terms of higher IL-1beta levels. Each exacerbation of acute disease in recurrent otitis media is likely to be mediated by IL-1beta. SIGNIFICANCE: We were able to clarify that recurrent OME is a stage that occurs before chronic OME. Therefore, the prevention of acute attacks in recurrent disease would also impede long-term damage to the middle ear.

Age Factors↗
PubMed2003

Persistent low levels of human chorionic gonadotropin: A premalignant gestational trophoblastic disease.

OBJECTIVE: This study was undertaken to evaluate the significance of persistent low-level human chorionic gonadotropin (hCG) titers (usually <50 IU/L) in the absence of clinical evidence of pregnancy or gestational trophoblastic disease. STUDY DESIGN: The USA hCG Reference Service consulted on 114 cases with persistent low levels of hCG; 51 had false-positive hCG results. The remaining 63 cases had real hCG results and are presented here. RESULTS: Antecedent gestational events included hydatidiform mole (27), pregnancy (35), and gestational trophoblastic neoplasm (1). Forty of the 63 (64%) cases received therapy, including chemotherapy (38), hysterectomy (2), or both (10). Despite treatment, in all cases, low hCG titers persisted. After 1 to 4.5 years of low titers, four women had a sudden rapid increase in hCG levels, and malignant disease was confirmed or clearly suggested (gestational trophoblastic neoplasm [3] and placental site trophoblastic tumor [1]). Invasive trophoblast antigen (ITA) is a marker of invasive cytotrophoblast cells. ITA was measured in 38 of the cases with persistent low hCG, in all cases ITA accounted for less than 25% of the hCG concentration. It was also determined in the 4 cases indicated with malignant disease, accounting for more than 80% of the hCG. CONCLUSION: The presence of persistent low-level hCG titers defines a subset of women with preinvasive or quiescent gestational trophoblastic disease. ITA effectively detected the presence or absence of invasive cells in these cases. The recommended management of the quiescent disease is close surveillance without therapy until malignant disease detected.

Chorionic Gonadotropin↗
PubMed2004

Plasticity and tuning of the time course of analog persistent firing in a neural integrator.

In a companion paper, we reported that the goldfish oculomotor neural integrator could be trained to instability or leak by rotating the visual surround with a velocity proportional to +/- horizontal eye position, respectively. Here we analyze changes in the firing rate behavior of neurons in area I in the caudal brainstem, a central component of the oculomotor neural integrator. Persistent firing could be detuned to instability and leak, respectively, along with fixation behavior. Prolonged training could reduce the time constant of persistent firing of some cells by more than an order of magnitude, to <1 s. Normal visual feedback gradually retuned persistent firing of integrator neurons toward stability, along with fixation behavior. In animals with unstable fixations, approximately half of the eye position-related cells had upward or unstable firing rate drift. In animals with leaky fixations, two-thirds of the eye position-related cells showed leaky firing drift. The remaining eye position-related cells, generally those with lower eye position thresholds, showed a more complex pattern of history-dependent/predictive firing rate drift in relation to eye drift. These complex drift cells often showed a drop in maximum persistent firing rate after training to leak. Despite this diversity, firing drift and the degree of instability or leak in firing rates were broadly correlated with fixation performance. The presence, strength, and reversibility of this plasticity demonstrate that, in this system, visual feedback plays a vital role in gradually tuning the time course of persistent neural firing.

Animals↗
PubMed2005

bptA (bbe16) is essential for the persistence of the Lyme disease spirochete, Borrelia burgdorferi, in its natural tick vector.

Borrelia burgdorferi (Bb), the agent of Lyme disease, is a zoonotic spirochetal bacterium that depends on arthropod (Ixodes ticks) and mammalian (rodent) hosts for its persistence in nature. The quest to identify borrelial genes responsible for Bb's parasitic dependence on these two diverse hosts has been hampered by limitations in the ability to genetically manipulate virulent strains of Bb. Despite this constraint, we report herein the inactivation and genetic complementation of a linear plasmid-25-encoded gene (bbe16) to assess its role in the virulence, pathogenesis, and survival of Bb during its natural life cycle. bbe16 was found to potentiate the virulence of Bb in the murine model of Lyme borreliosis and was essential for the persistence of Bb in Ixodes scapularis ticks. As such, we have renamed bbe16 a gene encoding borrelial persistence in ticks (bpt)A. Although protease accessibility experiments suggested that BptA as a putative lipoprotein is surface-exposed on the outer membrane of Bb, the molecular mechanism(s) by which BptA promotes Bb persistence within its tick vector remains to be elucidated. BptA also was shown to be highly conserved (>88% similarity and >74% identity at the deduced amino acid levels) in all Bb sensu lato strains tested, suggesting that BptA may be widely used by Lyme borreliosis spirochetes for persistence in nature. Given Bb's absolute dependence on and intimate association with its arthropod and mammalian hosts, BptA should be considered a virulence factor critical for Bb's overall parasitic strategy.

Animals↗
PubMed2005

Persistence of HIV-1 structural proteins and glycoproteins in lymph nodes of patients under highly active antiretroviral therapy.

Here we report a long-term persistence of HIV-1 structural proteins and glycoproteins in germinal centers (GCs) of lymph nodes (LNs) in the absence of detectable virus replication in patients under highly active antiretroviral therapy (HAART). The persistence of viral structural proteins and glycoproteins in GCs was accompanied by specific antibody responses to HIV-1. Seven patients during the chronic phase of HIV-1 infection were analyzed for the presence of the capsid protein (HIV-1p24), matrix protein (HIV-1p17), and envelope glycoproteins (HIV-1gp120/gp41), as well as for viral RNA (vRNA) in biopsy specimens from LNs obtained before initiation of therapy and during HAART that lasted from 5 to 13 months. In parallel, these patients were also monitored for viremia and specific anti-HIV-1 antibody responses to structural proteins and glycoproteins both before and during treatment. Before-therapy viral levels, as determined by RT-PCR, ranged from 3 x 10(3) to 6.3 x 10(5) copies of vRNA per ml, whereas during treatment, vRNA was under detectable levels (<25 copies per ml). The pattern of vRNA detection in peripheral blood was concordant with in situ hybridization results of LN specimens. Before treatment, vRNA associated with follicular dendritic cells (FDCs) was readily detected in GCs of LNs of the patients, whereas during therapy, vRNA was consistently absent in the GCs of LN biopsies of treated patients. In contrast to vRNA hybridization results, viral structural proteins and glycoproteins, evaluated by immunohistochemical staining, were present and persisted in the GC light zone of LNs in abundant amounts not only before initiation of therapy but also during HAART, when no vRNA was detected in GCs. Consistent with immunohistochemical findings, specific antibody responses to HIV-1p17, -p24, and -gp120/gp41, as evaluated by ELISA and virus neutralization, persisted in patients under therapy for up to 13 months of follow-up. The implications of these findings are discussed in relation to HIV-1 persistence in infected individuals and the potential role of chronic antigenic stimulation by the deposited structural proteins in GCs for AIDS-associated B cell malignancies.

Antiretroviral Therapy, Highly Active↗
PubMed2001

Mycobacterium tuberculosis signal transduction system required for persistent infections.

It is estimated that nearly 2 billion people currently suffer from latent Mycobacterium tuberculosis infection. Although the key front-line antituberculosis drugs are effective in treating individuals with acute tuberculosis, these drugs are ineffective in eliminating M. tuberculosis during the persistent stages of latent infection. Consequently, therapeutics that directly target persistent bacilli are urgently needed. We have conducted a global analysis on a group of regulatory determinants that may play a role in M. tuberculosis virulence, and identified a two-component response regulator whose expression is required for entrance into and maintenance of persistent infection. Inactivation of this response regulator, Rv0981 (termed here mprA for mycobacterial persistence regulator), affected M. tuberculosis H37Rv growth in vivo in an organ- and infection stage-specific fashion. These results indicate that two-component systems are important for adaptation of the tubercle bacillus during stages of persistent infection.

Animals↗
PubMed1986

Phosphatidylinositol 4,5-bisphosphate turnover is transient while phosphatidylinositol turnover is persistent in thyrotropin-releasing hormone-stimulated rat pituitary cells.

Stimulated inositolphospholipid turnover has been proposed to be initiated and sustained by hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], which may be replenished by an enhanced flux of phosphatidylinositol (PtdIns) to PtdIns 4-phosphate (PtdIns4P) to PtdIns(4,5)P2. To determine whether there is continued hydrolysis and resynthesis of PtdIns(4,5)P2 in rat pituitary cells (GH3 cells) during stimulation by thyrotropin-releasing hormone (TRH), we investigated the turnover kinetics of the inositolphospholipids and of phosphatidic acid (PtdOH). In cells incubated with 32Pi for 1 min, TRH rapidly and persistently (for at least 30 min) enhanced the rate of 32P-labeling of PtdOH. After a lag time of 1 min, TRH markedly and persistently increased 32P-labeling of PtdIns also. In contrast, TRH caused only a transient increase in 32P-labeling of PtdIns(4,5)P2 that lasted less than 2 min. There was no rapid (before 10 min) effect of TRH on 32P-labeling of PtdIns4P. By 2 min of TRH stimulation, specific 32P radioactivity in PtdOH increased from 3.6% (control) of that in the gamma-phosphate of ATP to 15%; in PtdIns, from 0.07% to 1.3%; and in PtdIns(4,5)P2, from 3.8% to 5.4% (specific 32P radioactivity in PtdIns4P was 1.7% of that in ATP in control and TRH-stimulated cells). In cells exposed to TRH for 4 min and then to 32Pi, 32P-labeling of PtdOH and PtdIns increased, but that of PtdIns(4,5)P2 was not affected. Last, persistent turnover of PtdOH and PtdIns was not caused by initial hydrolysis of PtdIns(4,5)P2 because the turnover of PtdOH and PtdIns could be terminated by displacement of TRH from its receptor by chlordiazepoxide and restarted by reoccupying the receptors with TRH. These data demonstrate that turnover of PtdIns(4,5)P2 is stimulated only transiently, whereas turnover of PtdIns and PtdOH is stimulated persistently by TRH in GH3 cells. Hence, inositolphospholipid turnover in GH3 cells does not occur via continued hydrolysis of PtdIns(4,5)P2 accompanied by enhanced flux of PtdIns to PtdIns4P to PtdIns(4,5)P2, but there is direct and persistent hydrolysis of PtdIns. The dissociation of these actions suggests that there are separate mechanisms involved in coupling TRH-receptor complexes to stimulation of PtdIns(4,5)P2 and PtdIns hydrolysis in GH3 cells.

Animals↗
PubMed1993

A simple direct method for finding persistence times of populations and application to conservation problems.

The computation of persistence times of populations has become a central focus in conservation biology. We describe a simple, direct method for finding the statistics of persistence times by assuming that there is a maximum population size. Thus, even though the population dynamics may be very complex for population sizes below the maximum, it is possible to write a finite set of equations from which the mean and second moment of the persistence time can be found by using simple, algebraic methods. We apply the method to compute the mean and coefficient of variation of persistence times of populations that suffer large decrements (catastrophes). Our results show that in the presence of catastrophes, the increase in mean persistence time with large populations is not nearly as rapid as other theories suggest and that catastrophes occurring at even modest rates can considerably increase the risk of extinction.

Journal Article↗
PubMed1994

Persistent diarrhoea: efficacy of a rice-based diet and role of nutritional status in recovery and nutrient absorption.

A diet based on rice powder, soya-bean oil, glucose, egg-white and salts was given to twenty-six patients of different nutritional status aged 4-18 months with persistent diarrhoea and twenty-five age-matched controls without diarrhoea. Clinical response was monitored during 1 week of dietary treatment and absorption of macronutrients was estimated during a 72 h balance study. Twenty-one patients (81%) recovered from diarrhoea within 7 d. There were significant relationships between nutritional indices, recovery, and absorption of total energy, fat and N. The absorption of fat, protein and carbohydrate in the better nourished controls without diarrhoea was significantly higher than in patients with persistent diarrhoea with better nutrition or malnutrition. The duration of diarrhoea was significantly longer in lighter patients (weight-for-age < 65% NCHS (1976) standard), in wasted patients (weight/height < 80% of NCHS) and those with mid upper arm circumference (MUAC) less than 110 mm. There were negative relationships between the period of recovery and the coefficient of absorption of fat (P < 0.001), total energy intake (P < 0.01) and MUAC (P < 0.05). Weight-for-age and MUAC showed most effective discriminative power for absorption of nutrients. However, the coefficients of absorption for carbohydrate were not different for any pair of nutritional groups. Absorption of all nutrients was also correlated negatively with severity of persistent diarrhoea on admission. The results of the present study indicate that a rice-based diet is highly effective in the management of persistent diarrhoea and less malnutrition aggravates nutrient malabsorption, increases duration and severity of diarrhoea and less severely malnourished patients do not absorb nutrients as well as healthy controls. Malnutrition and the initial severity of diarrhoea are significant determinants of clinical prognosis and nutrient absorption in persistent diarrhoea.

Body Weight↗
PubMed2001

Mixed leishmanial infections in Rhombomys opimus: a key to the persistence of Leishmania major from one transmission season to the next.

An important feature of the foci of zoonotic cutaneous leishmaniasis (ZCL) in Turkmenistan and Uzbekistan is a 6-10-month break in transmission when Leishmania parasites persist in great gerbils (Rhombomys opimus)--the main host for three species (L. major, L. turanica and L. gerbilli). Almost all (95%) of the laboratory-maintained R. opimus experimentally infected with L. major cured their infections within 6 months, a situation which, if mirrored in field conditions, cannot provide reliable persistence of the infection to the next transmission season. However, infections with L. turanica alone persisted for a mean of 15 months, and mixed infections of L. major and L. turanica persisted even longer (mean = 25 months), parasites of both species remaining detectable in the skin for at least 18 months. Isoenzyme identification of 664 isolates obtained from wild-caught R. opimus, and of 58 cloned strains developed from them, showed that L. turanica, which is non-pathogenic for humans, tends to predominate in the gerbils from all types of natural ZCL foci, including those which are hyper-endemic; in June, L. turanica may be present in 80%-100% of the R. opimus in the foci. In contrast, infections with L. major alone occur far less commonly, and are especially hard to find at the beginning of the transmission season. However, 5%-25% of great gerbils in these foci are each infected with a mixture of L. major and L. turanica. In hyper- and meso-endemic foci, the proportion of L. major within mixed infections of Leishmania increases significantly towards the end of transmission season (August-September). It would appear, therefore, that mixed L. major/L. turanica infections in R. opimus promote the persistence of L. major between transmission seasons.

Animals↗
PubMed1996

Using standard situations to measure attention span and persistence in toddler-aged children: some cautions.

This study was conducted with 38 children, 23-25 months old, to evaluate the use of standard situations to measure individuals differences in attention span and persistence. A vigilance task was used to measure attention span and three problem-solving tasks to measure persistence. Three delay tasks were used to measure inhibitory control, a personality trait hypothesized to be a correlate of attention span and persistence. Results showed (a) some consistency in performance within the persistence tasks but not across these tasks, (b) poor consistency in performance within the vigilance task, and (c) good consistency in performance across the delay tasks. No significant interrelations were found among the persistence, attention span, and delay measures. Developmental status, as measured by maternal report, was not related to any of the measures.

Attention↗
PubMed2004

Persistent retention of acetic acid is associated with complete tumour necrosis in patients with hepatocellular carcinoma undergoing percutaneous acetic acid injection.

BACKGROUND: Ultrasound (US)-guided percutaneous acetic acid injection therapy (PAIT) is effective for patients with hepatocellular carcinoma (HCC). This study aimed to determine the occurrence and predictive value of persistent intra-tumoral retention of acetic acid after PAIT. METHODS: We prospectively studied 60 (52 M, mean age 68 +/- 10 years) patients with 72 HCC nodules (45 < or = 3 cm) treated with PAIT. The presence of post-treatment persistent retention of acetic acid, defined as a homogeneous and highly hyperechoid mass in US appearance 3 days after completion of the treatment, was correlated with the treatment response. RESULTS: The mean size of the treated tumour was 2.9 +/- 1.0 cm (range 1.5-5 cm). Thirty (42%) HCC nodules showed complete tumour necrosis demonstrated by contrast-enhanced dynamic CT. Complete response was found in 22 (69%) of 32 nodules showing persistent intra-tumoral retention of acetic acid (P < 0.001). Small (< or = 3 cm) tumour size was also significantly associated with complete tumour necrosis (P = 0.001). There were no significant differences of the injection volume and treatment sessions between those with and without complete tumour necrosis in either small or large (> 3 cm) HCC (P > 0.1). Multivariate logistic regression analysis showed that persistent retention of acetic acid (odds ratio (OR) 10.4, 95% confidence interval (CI) 3.1-34.7; P < 0.001) and tumour size < or = 3 cm (OR 6.8, 95%, CI 1.8-25.8; P = 0.002) were independent factors predicting complete tumour necrosis. CONCLUSIONS: The presence of persistent retention of acetic acid is associated with a favourable response and may predict complete tumour necrosis after PAIT.

Acetic Acid↗
PubMed1998

Neuroticism in relation to recovery and persisting pain after laparoscopic cholecystectomy.

BACKGROUND: Persisting pain is seen in 20%-30% of patients after cholecystectomy for symptomatic gallbladder stones. The only preoperative factor that seems predictive is psychic vulnerability or neuroticism. Findings with regard to the influence of psychologic factors on recovery are contradictory, too. The aim of the present study was to examine a possible relationship between neuroticism and recovery and the outcome of operation. METHODS: Ninety-four patients who had had a laparoscopic cholecystectomy performed were tested psychologically with a Danish psychic vulnerability scale and with the Eysenck Neuroticism Scale before and 1 year after operation. The course of recovery was registered 1 month after operation, and outcome with regard to persisting pain 1 year postoperatively. RESULTS: No correlations were found between neuroticism scores and postoperative hospital stay or time to regain work/normal activities (P > 0.05). Persisting pain was found in 18% of the patients 1 year after operation. Although the patients with persisting pain had higher neuroticism scores preoperatively, the difference from the patients with successful outcome of the operation first became statistically significant 1 year postoperatively (P < 0.01-0.05). CONCLUSIONS: The results do not indicate that neuroticism influences the short recovery process after laparoscopic cholecystectomy. With regard to persisting pain, the higher neuroticism scores in these patients 1 year after the operation could be the consequence of the pain rather than aetiologic factors.

Adolescent↗
PubMed1989

Influence of perceived competence and causal dimension orientation on expectations, persistence, and performance during perceived failure.

This investigation was conducted to compare the influence of high and low perceived competence (PC) and various causal dimension orientations on expectations, persistence, and performance while perceiving failure on a motor task. Based on a response to a PC scale, 84 junior high school students were selected to participate in this study. Separately, 42 low and 42 high PC subjects were oriented to perceive their performance on a stabilometer balancing task as due to: (a) internal, controllable, unstable factors (ICU); (b) internal, uncontrollable, stable factors (IUS); or (c) nothing in particular (NDO). Subjects then received fictitious negative feedback over 15 trials. Results revealed that persistence, expectations, and performance dependent measures were significant for PC and Causal Dimension groups. More specifically, the High PC group persisted longer, had higher expectations, and performed significantly better than the Low PC group. Furthermore, the subjects presented ICU orientations persisted for a longer amount of time, revealed higher expectations over trials, and performed significantly better over trials than the subjects in the IUS and NDO groups. These findings suggest that perceived competence and causal dimensional orientations influence children's expectations, persistence, and performance when perceiving failure on a motor task.

Achievement↗
PubMed1982

Persistence and mobility of nitrofen (niclofen, TOK) in mineral and organic soils.

Residues of nitrofen in farm soils, persistence of nitrofen in field microplots, mobility of nitrofen in natural soils and the role of microbial flora in its degradation were studied. Muck soils from vegetable farms in southwestern Ontario contained up to 35 ppm nitrofen in mid-season (August), which decreased to 18 ppm by October. The herbicide was less persistent in sand than in muck. Degradation was slightly faster in sand and muck soils receiving two sprays, than in those sprayed once. From an initial deposit of ca. 2 and 10 ppm resp., in sand and muck field microplots, ca. 2 and 15% persisted after 16 wk. Leaching of nitrofen by water through sand was negligible, and it was even more strongly adsorbed onto organic soil. Natural microbial flora seemed to play an important role in the degradation of nitrofen in soil. Ca. 15 and 38% resp., of the initial concentration persisted in natural sandy loam and muck 16 wk after treatment at 10 ppm, whereas about 94 and 82% resp., persisted in sterilized sandy loam and muck at the same period.

Herbicides↗
PubMed2006

Associated factors and outcomes of persistent occiput posterior position: A retrospective cohort study from 1976 to 2001.

OBJECTIVE: To identify maternal and fetal risk factors associated with persistent occiput posterior position at delivery, and to examine the association of occiput posterior position with subsequent obstetric outcomes. METHODS: This is a retrospective cohort study of 30 839 term, cephalic, singleton births. Women with persistent occiput posterior (OP) position at delivery were compared to those with occiput anterior (OA) position. Demographics, obstetric history, and labor management were evaluated and subsequent obstetric outcomes examined. Potential confounding variables were controlled for using multivariate logistic regression analysis. RESULTS: The overall frequency of OP position was 8.3% in the study population. When compared to Caucasians, a higher rate of OP was observed among African-Americans (OR = 1.4, 95% CI 1.25-1.64) while no other racial/ethnic differences were noted. Other associated factors included nulliparity, maternal age > or =35, gestational age > or =41 weeks, and birth weight >4000 g, as well as artificial rupture of the membranes (AROM) and epidural anesthesia (p < 0.001 for all). Persistent OP was associated with increased rates of operative vaginal (OR = 4.14, 95% CI 3.57-4.81) and cesarean deliveries (OR = 13.45, 95% CI 11.94-15.15) and other peripartum complications including third or fourth degree perineal lacerations (OR = 2.38, 95% CI 2.03-2.79), and chorioamnionitis (OR = 2.10, 95% CI 1.81-2.44). CONCLUSION: Epidural use, AROM, African-American ethnicity, nulliparity, and birth weight >4000 g are associated with persistent OP position at delivery, with higher rates of operative deliveries and obstetric complications. This information can be useful in counseling patients regarding risks and associated outcomes of persistent OP position.

Adult↗
PubMed2000

Psychosocial correlates of cigarette smoking abstinence, experimentation, persistence and frequency during adolescence.

The purpose of this cross-sectional study was to examine and to compare the psychosocial characteristics associated with four dimensions of smoking: abstinence (never vs. ever), experimentation, frequency (daily vs. non-daily), and persistence (former vs. current). Persistent smokers (1 or more years) were contrasted with those who had been able to stop smoking for 1 year or more. From a sample of high school students who were assessed on two occasions (n = 1507), six smoking groups were defined: never smokers (n = 862), experimenters (n = 235), former non-daily (n = 80), current non-daily (n = 73), former daily (n = 71), and current daily (n = 110). The association between the four smoking dimensions and demographic, psychopathology, and psychosocial variables were examined. Differences between the never smokers and the experimenters were relatively small; albeit even minimal use of cigarettes is associated with some level of problems. As found in previous studies, smokers compared to never-smokers had substantially higher scores on most indices of dysfunction. Both frequent and persistent smoking was associated with higher lifetime prevalence of drug abuse/dependence and having more friends who smoke. Smoking persistence was uniquely related to greater conflict with parents and more problematic academic behavior. Smoking frequency was uniquely associated with higher impulsiveness. Gender did not significantly moderate the associations between smoking status and the psychosocial functioning. To the extent that there were differences between the characteristics associated with frequency and persistence, the results have implications for the design of interventions aimed at these dimensions.

Adaptation, Psychological↗
PubMed2002

Potential effects of certain persistent organic pollutants and endocrine disrupting chemicals on the health of children.

Persistent organic pollutants are lipophilic, man-made chemicals that are highly resistant to degradation. Due to their persistence, they have become distributed in small quantities throughout the world. They bioaccumulate in thefood chain and are stored in fatty tissues. Biomagnifications up the food chain result in potential widespread human exposure to these chemicals. Exposure to persistent organic pollutants has been associated with many adverse human health effects, including impaired neurodevelopment, immune and reproductive function. Many persistent organic pollutants also possess the ability to disrupt the normal functioning of the endocrine system. There is an increasing concern that low-level exposure to these endocrine disrupting chemicals may have adverse health impacts, particularly during fetal, neonatal, and childhood development. Both the nature and severity of health outcomes may depend on the developmental time-period during which chemical exposure occurs. This report summarizes scientific evidence on health effects of low-level exposure to persistent organic pollutants and endocrine disrupting chemicals.

Animals↗