Long-term outcomes after new onset seizure in children living with HIV: A cohort study

OBJECTIVE

To determine the long-term outcomes, including mortality and recurrent seizures, among children living with HIV (CLWH) who present with new onset seizure.

METHODS

Zambian CLWH and new onset seizure were enrolled prospectively to determine the risk of and risk factors for recurrent seizures. Demographic data, clinical profiles, index seizure etiology, and 30-day mortality outcomes were previously reported. After discharge, children were followed quarterly to identify recurrent seizures and death. Given the high risk of early death, risk factors for recurrent seizure were evaluated using a model that adjusted for mortality.

RESULTS

Among 73 children enrolled, 28 died (38%), 22 within 30-days of the index seizure. Median follow-up was 533 days (IQR 18-957) with 5% (4/73) lost to follow-up. Seizure recurrence was 19% among the entire cohort. Among children surviving at least 30-days after the index seizure, 27% had a recurrent seizure. Median time from index seizure to recurrent seizure was 161 days (IQR 86-269). Central nervous system opportunistic infection (CNS OI), as the cause for the index seizure was protective against recurrent seizures and higher functional status was a risk factor for seizure recurrence.

SIGNIFICANCE

Among CLWH presenting with new onset seizure, mortality risks remain elevated beyond the acute illness period. Recurrent seizures are common and are more likely in children with higher level of functioning even after adjusting for the outcome of death. Newer antiseizure medications appropriate for co-usage with antiretroviral therapies are needed for the care of these children. CNS OI may represent a potentially reversible provocation for the index seizure, while seizures in high functioning CLWH without a CNS OI may be the result of a prior brain injury or susceptibility to seizures unrelated to HIV and thus represent an ongoing predisposition to seizures.

PLAIN LANGUAGE SUMMARY

This study followed CLWH who experienced a new onset seizure to find out how many go on to have more seizures and identify any patient characteristics associated with having more seizures. The study found that mortality rates continue to be high beyond the acute clinical presentation with new onset seizure. Children with a CNS OI causing the new onset seizure had a lower risk of later seizures, possibly because the trigger for the seizure can be treated. In contrast, high functioning children without a CNS OI were at higher risk of future seizures.

Patient, Provider, and Health Systems Factors Leading to Lumbar Puncture Nonperformance in Zambia: A Qualitative Investigation of the "Tap Gap"

Lumbar puncture (LP) and cerebrospinal fluid (CSF) diagnostics are critical for evaluating central nervous system infections but are often not conducted, resulting in the "Tap Gap." To investigate patient, provider, and health systems factors contributing to the Tap Gap in Zambia, we conducted focus group discussions with adult caregivers of hospitalized inpatients and in-depth interviews with nurses, clinicians, pharmacy workers, and laboratory staff. Transcripts were independently thematically categorized by two investigators using inductive coding. We identified seven patient-related factors: 1) alternative understandings of CSF; 2) alternative information about LPs, including misinformation; 3) mistrust of doctors; 4) consent delays; 5) fear of blame; 6) peer pressure against consent; and 7) association between LP and stigmatized conditions. Four clinician-related factors were identified: 1) limited LP knowledge and expertise, 2) time constraints, 3) delays in LP requests by clinicians, and 4) fear of blame for bad outcomes. Finally, five health systems-related factors were identified: 1) supply shortages, 2) constrained access to neuroimaging, 3) laboratory factors, 4) availability of antimicrobial medications, and 5) cost barriers. Efforts to improve LP uptake must incorporate interventions to increase patient/proxy willingness to consent and improve clinician LP competencies while addressing both upstream and downstream health system factors. Key upstream factors include inconsistently available consumables for performing LPs and lack of neuroimaging. Critical downstream factors include laboratory services that offer poor availability, reliability, and/or timeliness of CSF diagnostics and the reality that medications needed to treat diagnosed infections are often unavailable unless the family has resources to purchase privately.

Designing an Observing System to Study the Surface Biology and Geology (SBG) of the Earth in the 2020s

Observations of planet Earth from space are a critical resource for science and society. Satellite measurements represent very large investments and United States (US) agencies organize their effort to maximize the return on that investment. The US National Research Council conducts a survey of Earth science and applications to prioritize observations for the coming decade. The most recent survey prioritized a visible to shortwave infrared imaging spectrometer and a multispectral thermal infrared imager to meet a range of needs for studying Surface Biology and Geology (SBG). SBG will be the premier integrated observatory for observing the emerging impacts of climate change by characterizing the diversity of plant life and resolving chemical and physiological signatures. It will address wildfire risk, behavior, and recovery as well as responses to hazards such as oil spills, toxic minerals in minelands, harmful algal blooms, landslides, and other geological hazards. The SBG team analyzed needed instrument characteristics (spatial, temporal, and spectral resolutions, measurement uncertainty) and assessed the cost, mass, power, volume, and risk of different architectures. We present an overview of the Research and Applications trade-study analysis of algorithms, calibration and validation needs, and societal applications with specifics of substudies detailed in other articles in this special collection. We provide a value framework to converge from hundreds down to three candidate architectures recommended for development. The analysis identified valuable opportunities for international collaboration to increase the revisit frequency, adding value for all partners, leading to a clear measurement strategy for an observing system architecture.

Clinical characteristics and outcomes after new-onset seizure among Zambian children with HIV during the antiretroviral therapy era

OBJECTIVE

This study describes clinical profiles including human immunodeficiency virus (HIV) disease history and seizure etiology among children living with HIV presenting with new-onset seizure during the era of antiretroviral therapy (ART) in Zambia. 30-day mortality and cause of death are also reported.

METHODS

Children living with HIV (CLWHIV) with new-onset seizures were prospectively evaluated at one large urban teaching hospital and two non-urban healthcare facilities. Interviews with family members, review of medical records, and where needed, verbal autopsies were undertaken. Two clinicians who were not responsible for the patients' care independently reviewed all records and assigned seizure etiology and cause of death with adjudication as needed.

RESULTS

From April 2016 to June 2019, 73 children (49 urban, 24 rural) were identified. Median age was 6 years (IQR 2.2-10.0) and 39 (53%) were male children. Seizures were focal in 36 (49%) and were often severe, with 37% presenting with multiple recurrent seizures in the 24 hours before admission or in status epilepticus. Although 36 (49%) were on ART at enrollment, only 7 of 36 (19%) were virally suppressed. Seizure etiologies were infectious in over half (54%), with HIV encephalitis, bacterial meningitis, and tuberculous meningitis being the most common. Metabolic causes (19%) included renal failure and hypoglycemia. Structural lesions identified on imaging accounted for 10% of etiologies and included stroke and non-accidental trauma. No etiology could be identified in 12 (16%) children, most of whom died before the completion of clinical investigations. Twenty-two (30%) children died within 30 days of the index seizure.

SIGNIFICANCE

Despite widespread ART roll out in Zambia, new-onset seizure in CLWHIV occurs in the setting of advanced, active HIV disease. Seizure severity/burden is high as is early mortality. Enhanced programs to assure early ART initiation, improve adherence, and address ART failure are needed to reduce the burden of neurological injury and premature death in CLWHIV.

Neuropathogenesis of severe acute respiratory syndrome coronavirus 2

PURPOSE OF REVIEW

The purpose of this review is to address our current understanding of the pathophysiology of neurologic injury resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection on the developing nervous system.

RECENT FINDINGS

SARS-CoV2 may enter the brain through three potential mechanisms: transsynaptic spread from the olfactory bulb following intranasal exposure, migration across the blood-brain barrier through endothelial cell infection, and migration following disruption of the blood-brain barrier from resulting inflammation. SARS-CoV2 does not appear to directly infect neurons but rather may produce an inflammatory cascade that results in neuronal injury. Additionally, autoantibodies targeting neuronal tissue resulting from the immune response to SARS-CoV2 are present in select patients and may contribute to central nervous system (CNS) injury.

SUMMARY

These findings suggest that neuronal injury during SARS-CoV2 infection is immune mediated rather than through direct viral invasion. Further multimodal studies evaluating the pathophysiology of neurologic conditions in pediatric patients specifically following SARS-CoV2 infection are needed to improve our understanding of mechanisms driving neurologic injury and to identify potential treatment options.

Factors Associated with Lumbar Puncture Performance in Zambia

In much of sub-Saharan Africa, lumbar punctures (LPs) are performed less frequently than indicated. This is often attributed to patient/family refusal; however, other factors have not been systematically evaluated. We investigated predictors of LP performance for a prospective cohort of people with HIV and new-onset seizures at three hospitals in Zambia. We enrolled 257 participants, including 184 (72%) adults and 144 (56%) urban participants. LPs were performed for 65% of adults and 33% of children, and for 69% of urban and 38% of rural participants. In multivariate logistic regression analyses, LP completion was significantly less likely at one rural site and among children compared to adults. The Worst WHO HIV disease stage was associated with increased odds of undergoing LP. Low LP completion rates in Zambia are multifactorial and related to health system and provider factors and patient/family preferences. Further research is necessary to understand this complex problem and develop interventions to improve LP uptake.

Genotype-phenotype correlations and novel molecular insights into the DHX30-associated neurodevelopmental disorders

Background

We aimed to define the clinical and variant spectrum and to provide novel molecular insights into the DHX30-associated neurodevelopmental disorder.

Methods

Clinical and genetic data from affected individuals were collected through Facebook-based family support group, GeneMatcher, and our network of collaborators. We investigated the impact of novel missense variants with respect to ATPase and helicase activity, stress granule (SG) formation, global translation, and their effect on embryonic development in zebrafish. SG formation was additionally analyzed in CRISPR/Cas9-mediated DHX30-deficient HEK293T and zebrafish models, along with in vivo behavioral assays.

Results

We identified 25 previously unreported individuals, ten of whom carry novel variants, two of which are recurrent, and provide evidence of gonadal mosaicism in one family. All 19 individuals harboring heterozygous missense variants within helicase core motifs (HCMs) have global developmental delay, intellectual disability, severe speech impairment, and gait abnormalities. These variants impair the ATPase and helicase activity of DHX30, trigger SG formation, interfere with global translation, and cause developmental defects in a zebrafish model. Notably, 4 individuals harboring heterozygous variants resulting either in haploinsufficiency or truncated proteins presented with a milder clinical course, similar to an individual harboring a de novo mosaic HCM missense variant. Functionally, we established DHX30 as an ATP-dependent RNA helicase and as an evolutionary conserved factor in SG assembly. Based on the clinical course, the variant location, and type we establish two distinct clinical subtypes. DHX30 loss-of-function variants cause a milder phenotype whereas a severe phenotype is caused by HCM missense variants that, in addition to the loss of ATPase and helicase activity, lead to a detrimental gain-of-function with respect to SG formation. Behavioral characterization of dhx30-deficient zebrafish revealed altered sleep-wake activity and social interaction, partially resembling the human phenotype.

Conclusions

Our study highlights the usefulness of social media to define novel Mendelian disorders and exemplifies how functional analyses accompanied by clinical and genetic findings can define clinically distinct subtypes for ultra-rare disorders. Such approaches require close interdisciplinary collaboration between families/legal representatives of the affected individuals, clinicians, molecular genetics diagnostic laboratories, and research laboratories.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00900-3.

A-41 Verbal Fluency and Switching Accuracy Differences in Pediatric Epilepsy Pre- and Post- Surgery

Objective

In patients with epilepsy, research is variable with regard to language difficulties. Previous research generally focuses on phonemic and semantic verbal fluency in pediatric populations post-surgery; however, few studies examine category switching accuracy. This study compared phonemic fluency, categorical fluency, switching accuracy, and the number of switches among pre-surgical and post-surgical groups.

Methods

Participants included 31 epilepsy patients (age 5-20 years old; M = 12.23 years pre-surgery; M = 14.72 years post-surgery; 20 males, 11 females) who underwent neuropsychological evaluations prior to and following open brain resection surgery (i.e., temporal lobectomy, temporal resection, frontal lobectomy). Verbal Fluency was assessed by the Delis-Kaplan Executive Functioning System (D-KEFS), measuring phonemic fluency, categorical fluency, switching accuracy, and the number of switches.

Results

Statistically significant differences were found between groups on the D-KEFS Verbal Fluency subtest using a one-way ANOVA. Specifically, switching accuracy decreased following surgery, F(1,25) = 6.470, p = 0.02 (M = 104.44 pre-surgery, M = 89.44 post-surgery). Further, a downward trend was noted regarding the number of switches between the two groups, F (1, 26) = 3.172, p = 0.09; however, no differences were found in phonemic, F(1,34) = 0.854, p = 0.63, and categorical, F(1,35) = 0.828, p = 0.37, fluency tasks.

Conclusions

Results from this study revealed a decrease in the participants ability to accurately switch between verbal categories following brain resection surgery. Similarly, a downward trend was noted for number of switches completed pre- and post- surgery. Consistent with previous research, phonemic and semantic verbal fluency tasks remain unchanged post-surgery. Implications of this study highlight the need to assess executive functioning after surgery as it has an impact on treatment outcome and school planning.

A-36 Cognitive Differences Between Children with New Onset Seizures and Those with Longer Seizure Histories

Objective

Epilepsy is associated with cognitive difficulties including language and memory problems. Studies examining cognitive function in children with new onset seizures have found that they have difficulties when compared to healthy controls, but less is known about how these difficulties compare to cognitive function in children who have had seizures for longer periods. Our study compared semantic memory and verbal fluency skills in a group of pediatric patients with new onset seizures (< 12 months) to a group of presurgical epilepsy patents who had seizures for more than 12 months.

Method

Participants included 12 new onset seizure patients (age 8–15 years old; M = 12.13 years, SD = 2.4; 58.3% male), and 14 presurgical epilepsy patients (age 8-18 years old; M = 13.26 years, SD = 3.3; 64.3% male) who underwent neuropsychological evaluations as part of their standard of care. All patients were recruited from a regional children’s hospital. Outcome variables included performance on the Boston Naming Test (BNT) and Delis-Kaplan Executive Function System Verbal Fluency test, Letter (LF) and Category (CF) Fluencies.

Results

Overall intellectual ability did not differ significantly between groups. No significant differences were found between the two groups on the BNT [F (17,2) = 1.012, p = .607], LF [F (8,16) = 1.375, p = .279], or CF [F (7,17) = .544, p = .790].

Conclusions

Findings indicating no significant differences on cognitive tasks between the two groups are consistent with previous research indicating that individuals with new onset seizures often exhibit cognitive difficulties at the time their seizures begin.

A-68 Yoga Therapy in Pediatric Epilepsy

Objective

This pilot study examines the effects of yoga therapy on anxiety, depression symptoms, inattention, and seizure frequency in children diagnosed with Epilepsy.

Data Selection

The sample consisted of 5 participants (4 male, 1 female), ages 7-12 years old, with diagnoses of generalized epilepsy, absence epilepsy, and complex partial epilepsy. Participants all had average cognitive abilities (IQ SS = 100.7; VCI SS = 106.3; PRI SS = 108.3), a diagnosis of Attention Deficit Hyperactivity Disorder (ADHD), and clinically significant levels of anxiety and depression. Participants participated in 30-45-minute-long yoga sessions over a 6-week period with 2-3 home sessions each week. Differences in hyperactivity, anxiety, depression, and inattention were measured via parent rating Likert scales (0-poor, 10-best) at 1 month, 3 months, and 6 months. Participants also completed weekly self-report measures to assess anxiety and depression (Revised Children’s Manifest Anxiety, Second Edition (RCMAS-2) and Children’s Depression Inventory, Second Edition (CDI-2)).

Data Synthesis

No significant reliable change differences were found between sessions; however, a downward trend was visible in reduction of anxiety (RCMAS-2; first session M = 16.4, last session M = 9.4) and depression symptoms (CDI-2; first session M = 52.8, last session M = 49.2). Further, parents reported a decrease in anxiety (first session M = 4.8, last session M = 6.4). No seizures were reported during the study.

Conclusions

There is no previous research using pediatric populations and yoga therapy effects on reducing seizure frequency, anxiety, depression, and attention problems. This pilot study showed promising results in reducing anxiety, and depression symptoms. Limitations of study include small sample size and attrition, which are both important to consider when conducting another study.

A-38 Examining Cognitive Differences of Pre- and Post- Surgery in Pediatric Epilepsy

Objective

Intractable epilepsy is often associated with cognitive difficulties in the language domain. Few studies examining verbal domains of cognitive functioning indicate a small increase of verbal skills post-surgery. The current study compared Verbal IQ and Performance IQ domains in pediatric populations before and after open resection surgery.

Method

Participants included 31 epilepsy patients (age 5-20 years old; M = 12.23 years pre-surgery; M = 14.72 years post-surgery; 20 males, 11 females) who underwent neuropsychological evaluations prior to and following an open brain resection surgery (i.e., temporal lobectomy, temporal resection, frontal lobectomy). Cognitive ability was assessed by Weschler Abbreviated Scale of Intelligence (WASI) in order to analyze differences between pre-surgical and post-surgical cognitive function, specifically verbal comprehension and perceptual reasoning ability.

Results

No statistically significant differences were found, using a One-way ANOVA, between the two groups; however, a downward trend was noted for the Verbal IQ (VIQ) domain, F(1, 25) = 2.624, p = 0.118, including the verbal subtests vocabulary, F(1, 23) = 2.203, p = 0.151, and similarities, F(1, 24) = 1.678, p = 0.207. No differences or trends were noted within the Performance IQ (PIQ) domain, block design, or matrix reasoning.

Conclusions

Findings indicated that participants verbal ability decreased after epilepsy surgery when compared to prior evaluations. This is not consistent with previous research, which stated an increase in verbal abilities following surgical resection. Variable time between surgery and re-evaluation might account for discrepancies. Further, no differences in nonverbal reasoning abilities were noted. Results indicated a need for further research in open brain resection surgeries and the outcome of verbal processing.

Treatment Responsiveness in KCNT1-Related Epilepsy

Pathogenic variants in KCNT1 represent an important cause of treatment-resistant epilepsy, for which an effective therapy has been elusive. Reports about the effectiveness of quinidine, a candidate precision therapy, have been mixed. We sought to evaluate the treatment responsiveness of patients with KCNT1-related epilepsy. We performed an observational study of 43 patients using a collaborative KCNT1 patient registry. We assessed treatment efficacy based upon clinical seizure reduction, side effects of quinidine therapy, and variant-specific responsiveness to treatment. Quinidine treatment resulted in a > 50% seizure reduction in 20% of patients, with rare patients achieving transient seizure freedom. Multiple other therapies demonstrated some success in reducing seizure frequency, including the ketogenic diet and vigabatrin, the latter particularly in patients with epileptic spasms. Patients with the best quinidine response had variants that clustered distal to the NADP domain within the RCK2 domain of the protein. Half of patients did not receive a quinidine trial. In those who did, nearly half did not achieve therapeutic blood levels. More favorable response to quinidine in patients with KCNT1 variants distal to the NADP domain within the RCK2 domain may suggest a variant-specific response.

Global developments in HIV neurology

Neurologic conditions associated with HIV remain major contributors to morbidity and mortality, and are increasingly recognized in the aging population on long-standing combination antiretroviral therapy (cART). Importantly, growing evidence suggests that the central nervous system (CNS) serves as a reservoir for viral replication with major implications for human immunodeficiency virus (HIV) eradication strategies. Though there has been major progress in the last decade in our understanding of the pathogenesis, burden, and impact of HIV-associated neurologic conditions, significant scientific gaps remain. In many low-income settings, second- and third-line cART regimens that carry substantial neurotoxicity remain treatment mainstays. Further, patients continue to present severely immunosuppressed with CNS opportunistic infections. Public health efforts should emphasize improvements in access and optimizing treatment of HIV-positive patients, specifically in resource-limited settings, to reduce the risk of neurologic sequelae.

Treatment of Chronic Enterovirus Encephalitis With Fluoxetine in a Patient With X-Linked Agammaglobulinemia

INTRODUCTION

Enterovirus may result in a devastating chronic encephalitis in immunocompromised patients, particularly in patients with X-linked agammaglobulinemia. Prognosis for patients with chronic enterovirus encephalitis is poor, almost invariably resulting in mortality without specific treatment. There are currently no approved antiviral agents for enterovirus, but the antidepressant drug fluoxetine has been identified through library-based compound screening as a potential anti-enteroviral agent in vitro. However, use of fluoxetine has not previously been studied in humans with enteroviral disease.

PATIENT DESCRIPTION

A five year old boy with X-linked agammaglobulinemia presented with progressive neurological deterioration and was found to have chronic enterovirus encephalitis by brain biopsy. He failed to respond to standard treatment with high dose intravenous immunoglobulin, but showed stabilization and improvement following treatment with fluoxetine.

CONCLUSIONS

This is the first report to describe the use of fluoxetine as a potential therapy for chronic enterovirus infection. Further investigation of fluoxetine as a treatment option for chronic enterovirus encephalitis is necessary.

Pediatric Cerebral Palsy in Africa: Where Are We?

Cerebral palsy is the most common cause of physical disability in children worldwide. However, little is reported on this condition in the African context. Doctors from 22 countries in Africa, and representatives from a further 5 countries outside Africa, met to discuss the challenges in the evaluation and management of children with cerebral palsy in Africa and to propose service needs and further research. Basic care is limited by the poor availability of diagnostic facilities or medical personnel with experience and expertise in managing cerebral palsy, exacerbated by lack of available interventions such as medications, surgical procedures, or even regular therapy input. Relevant guidelines are lacking. In order to guide services for children with existing disabilities, to effectively target the main etiologies and to develop preventive strategies for the continent, research priorities must include multicenter collaborative studies looking at the prevalence, risk factors, and treatment of cerebral palsy.

Severe 5,10-methylenetetrahydrofolate reductase deficiency and two MTHFR variants in an adolescent with progressive myoclonic epilepsy

BACKGROUND

5,10-Methylenetetrahydrofolate reductase (MTHFR) deficiency is an inborn error of the folate-recycling pathway that affects the remethylation of homocysteine to methionine. The clinical presentation of MTHFR deficiency is highly variable ranging from early neurological deterioration and death in infancy to a mild thrombophilia in adults.

PATIENT AND METHODS

We describe an adolescent girl with a history of mild learning disabilities who presented at age 14 years with an epilepsy syndrome initially thought to be juvenile myoclonic epilepsy. She later developed intractable epilepsy with myoclonus, leg weakness, cognitive decline, and ataxia consistent with the syndrome of progressive myoclonic epilepsy. This prompted further evaluation that revealed elevated plasma homocysteine and decreased plasma methionine. The diagnosis of MTHFR deficiency was confirmed based on extremely reduced fibroblast MTHFR activity (0.3 nmol CHO/mg prot/hr) as well as mutation analysis that revealed two variants in the MTHFR gene, a splice site mutation p (IVS5-1G>A), as well as a missense mutation (c.155 G>A; p. Arg52Gln). Therapy with folinic acid, betaine, and methionine has produced significant clinical improvement, including improved strength, less severe ataxia, and decreased seizure frequency, as well as improvements in her electroencephalography and electromyography.

CONCLUSION

This patient demonstrates the importance of considering MTHFR deficiency in the differential diagnosis of progressive myoclonic epilepsy because it is one of the few causes for which specific treatment is available.

Pediatric cerebral palsy in Africa: a systematic review

Cerebral palsy is a common neurologic problem in children and is reported as occurring in approximately 2-2.5 of 1000 live births globally. As is the case with many pediatric neurologic conditions, very little has been reported on this condition in the African context. Resource-limited settings such as those found across the continent are likely to result in a different spectrum of etiologies, prevalence, severity as well as management approaches. This review aims to establish what has been reported on this condition from the African continent so as to better define key clinical and research questions.

Isolated neonatal seizures: when to suspect inborn errors of metabolism

Neonatal seizures are common, and often comprise the first clinical indicator of central nervous system dysfunction. Although most neonatal seizures are secondary to processes such as hypoxic-ischemic injury, infection, or cortical malformations (which are readily identifiable through routine testing and imaging), seizures secondary to inborn errors of metabolism can be much more difficult to diagnose, and thus a high index of suspicion is required. The early diagnosis of inborn errors of metabolism is crucial, considering that many can receive effective treatment (e.g., dietary supplementation or restriction) with favorable long-term outcomes. This review emphasizes the importance of considering inborn errors of metabolism in the differential diagnosis of neonatal seizures, discusses red flags for inborn errors of metabolism as a cause of neonatal seizures, and provides an overview of diagnoses and treatments of inborn errors of metabolism most commonly associated with neonatal seizures.

An evaluation of contaminated estuarine sites using sediment quality guidelines and ecological assessment methodologies

Toxic contaminants may enter estuarine ecosystems through a variety of pathways. When sediment contaminant levels become sufficiently high, they may impact resident biota. One approach to predict sediment-associated toxicity in estuarine ecosystems involves the use of sediment quality guidelines (ERMs, ERLs) and site-specific contaminant chemistry while a second approach utilizes site-specific ecological sampling to assess impacts at the population or community level. The goal of this study was to utilize an integrated approach including chemical contaminant analysis, sediment quality guidelines and grass shrimp population monitoring to evaluate the impact of contaminants from industrial sources. Three impacted sites and one reference site were selected for study. Grass shrimp populations were sampled using a push-netting approach. Sediment samples were collected at each site and analyzed for metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides. Contaminant levels were then compared to sediment quality guidelines. In general, grass shrimp population densities at the sites decreased as the ERM quotients increased. Grass shrimp densities were significantly reduced at the impacted site that had an ERM exceedance for chromium and the highest Mean ERM quotient. Regression analysis indicated that sediment chromium concentrations were negatively correlated with grass shrimp density. Grass shrimp size was reduced at two sites with intermediate levels of contamination. These findings support the use of both sediment quality guidelines and site-specific population monitoring to evaluate the impacts of sediment-associated contaminants in estuarine systems.

An evaluation of polycyclic aromatic hydrocarbon (PAH) runoff from highways into estuarine wetlands of South Carolina

This study investigated the concentrations and potential toxicity of polycyclic aromatic hydrocarbons (PAHs) associated with highway runoff into adjacent estuarine wetlands from road segments representing three levels of average daily traffic (ADT): low (<5,000 ADT), moderate (10,000-15,000 ADT), and high use (>25,000 ADT) based on SC Department of Transportation data. Sediments from three estuarine wetland habitats (tidal creeks, Spartina marsh, and mud flats) adjacent to these road segments were sampled to represent nine highway use class/habitat type combinations. Surficial sediments were collected at 3, 25, and 50 meters from the upland/wetland interface along transects established perpendicular to the road at each site, with additional samples taken from the road berm. Average PAH concentrations, representing 25 compounds, ranged from 3.9 to 11,000 ng/g dry weight. Berm samples had significantly greater total PAH concentrations than samples taken in any of the wetland habitats. Average total PAH concentrations decreased with increasing distance from the road berm within the wetland habitats sampled, but the differences were not statistically significant. Average total PAH concentrations also were not significantly different among the wetland habitats compared. Analysis of PAH profiles indicated that the PAH source was dominated by pyrogenic combustion products rather than from petrogenic sources. This, combined with the presence of dibenzothio-phene, which is a tire oxidation product, indicated that the primary source of PAHs was related to vehicles. Two sites with total PAH concentrations exceeding published bioeffects levels were resampled for bioassay tests using the amphipod Ampelisca verrilli, the polychaete Streblospio benedicti, and the clam, Mercenaria mercenaria, with the first two assays conducted under UV lighting since previous studies had demonstrated enhanced UV toxicity of PAHs for these species. No toxicity was observed in the amphipod or polychaete assays. Toxicity was observed in the juvenile clam assay at one site, possibly due to the combined effects of PAHs and other contaminants present.

The effects of the contemporary-use insecticide (fipronil) in an estuarine mesocosm

To examine the effects of environmentally realistic fipronil concentrations on estuarine ecosystems, replicated mesocosms containing intact marsh plots and seawater were exposed to three treatments of fipronil (150, 355, and 5000 ng/L) and a Control. Juvenile fish (Cyprinidon variegatus), juvenile clams (Mercenaria mercenaria), oysters (Crassostrea virginica), and grass shrimp (Palaemonetes pugio) were added prior to fipronil in an effort to quantify survival, growth, and the persistence of toxicity during the planned 28-day exposure. Results indicated that there were no fipronil-associated effects on the clams, oysters, or fish. Shrimp were sensitive to the highest two concentrations (40% survival at 355 ng/L and 0% survival at 5000 ng/L). Additionally, the highest fipronil treatment (5000 ng/L) was toxic to shrimp for 6 weeks post dose. These results suggest that fipronil may impact shrimp populations at low concentrations and further use in coastal areas should be carefully assessed.

Toxicological studies in tropical ecosystems: an ecotoxicological risk assessment of pesticide runoff in South Florida estuarine ecosystems

A multiyear study in the C-111 canal system and associated sites in Florida Bay was undertaken to determine the potential pesticide risk that exists in South Florida. After the examination of extensive pesticide concentration data in surface water, tissues, and semipermeable membrane devices (SPMDs), canal contamination seems to be derived from the extensive agricultural production that drains into the C-111 canal. The results of this study indicate that runoff from agricultural processes led to quantifiable pesticide residues in both canal and bay surface water, which occasionally exceeded current water quality criteria. The major pesticide of concern was endosulfan, which was detected at 100% of the sites sampled. Endosulfan exposure did not cause any acute effects in fish and crustaceans deployed in field bioassays. Chronic effects were observed in copepods, clams, and oysters but could not be attributed to endosulfan exposure. The decision to alter the C-111 canal flow and allow increased freshwater flow into the adjacent Everglades National Park may result in discharges of pesticides into the Everglades. Continued monitoring in this area is needed during this change in flow regime.

The NDP-sugar co-substrate concentration and the enzyme expression level influence the substrate specificity of glycosyltransferases: cloning and characterization of deoxysugar biosynthetic genes of the urdamycin biosynthetic gene cluster

BACKGROUND

Streptomyces fradiae is the principal producer of urdamycin A. The antibiotic consists of a polyketide-derived aglycone, which is glycosylated with four sugar components, 2x D-olivose (first and last sugar of a C-glycosidically bound trisaccharide chain at the 9-position), and 2x L-rhodinose (in the middle of the trisaccharide chain and at the 12b-position). Limited information is available about both the biosynthesis of D-olivose and L-rhodinose and the influence of the concentration of both sugars on urdamycin biosynthesis.

RESULTS

To further investigate urdamycin biosynthesis, a 5.4 kb section of the urdamycin biosynthetic gene cluster was sequenced. Five new open reading frames (ORFs) (urdZ3, urdQ, urdR, urdS, urdT) could be identified each one showing significant homology to deoxysugar biosynthetic genes. We inactivated four of these newly allocated ORFs (urdZ3, urdQ, urdR, urdS) as well as urdZ1, a previously found putative deoxysugar biosynthetic gene. Inactivation of urdZ3, urdQ and urdZ1 prevented the mutant strains from producing L-rhodinose resulting in the accumulation of mainly urdamycinone B. Inactivation of urdR led to the formation of the novel urdamycin M, which carries a C-glycosidically attached D-rhodinose at the 9-position. The novel urdamycins N and O were detected after overexpression of urdGT1c in two different chromosomal urdGT1c deletion mutants. The mutants lacking urdS and urdQ accumulated various known diketopiperazines.

CONCLUSIONS

Analysis of deoxysugar biosynthetic genes of the urdamycin biosynthetic gene cluster revealed a widely common biosynthetic pathway leading to D-olivose and L-rhodinose. Several enzymes responsible for specific steps of this pathway could be assigned. The pathway had to be modified compared to earlier suggestions. Two glycosyltransferases normally involved in the C-glycosyltransfer of D-olivose at the 9-position (UrdGT2) and in conversion of 100-2 to urdamycin G (UrdGT1c) show relaxed substrate specificity for their activated deoxysugar co-substrate and their alcohol substrate, respectively. They can transfer activated D-rhodinose (instead of D-olivose) to the 9-position, and attach L-rhodinose to the 4A-position normally occupied by a D-olivose unit, respectively.

Age, race, and gender variation in the utilization of coronary artery bypass surgery and angioplasty in SHEP. SHEP Cooperative Research Group. Systolic Hypertension in the Elderly Program

OBJECTIVE

To assess variability in the use of coronary artery bypass grafting (CABG) and percutaneous transluminal angioplasty (PTCA) in the Systolic Hypertension in the Elderly Program (SHEP) cohort with incident coronary heart disease (CHD) by age, sex, and race.

DESIGN

Retrospective analysis of a multicenter prospective cohort study.

SETTING

Community-based ambulatory population in academic centers.

PATIENTS

Among 4736 subjects initially enrolled in SHEP, there were 432 incident cases of CHD, excluding those patients who experienced rapid or sudden cardiac death.

MAIN OUTCOME MEASURE

Incident cases of CHD who underwent CABG or PTCA.

RESULTS

Of those participants > or = 60 and < 75 years of age, 7.3% underwent PTCA, compared with 3.9% of those > or = 75 years (P = 0.14). 15.4% of those < 75 underwent CABG surgery, compared with 7.8% of those 75 and older (P = 0.018). When both of these endpoints, CABG and PTCA, were combined, 22.4% of those < 75 underwent a procedure, while only 11.7% of the older cohort did (P = 0.005). Twenty-six percent of men underwent either CABG or PTCA, while only 9.1% of women did (P < 0.001). Of those < 75 years of age, 31.1% of men and 12.3% of women underwent CABG or PTCA (P < 0.001). In the 75 and older age category, 19.5% of men underwent these interventions, compared with 5.9% of women (P = 0.005). Active treatment group was significantly associated with decreased use of procedures in participants < 75 year old with CHD. Race, activity limitations, number of comorbid conditions, education level, marital status, employment status, and social support were not significantly associated with CABG or PTCA use. When the variables studied were entered into a logistic regression model, increased age and female sex remained independently associated with decreased CABG and PTCA use.

CONCLUSION

In the SHEP trial older patients and women, regardless of comorbid conditions, socioeconomic status, and social support, underwent less intensive cardiovascular interventions than did younger patients and men when they developed CHD.