Agricultural paraquat dichloride use and Parkinson's disease in California's Central Valley

BACKGROUND

Paraquat dichloride is currently among the most widely used commercial herbicides in the USA. In the present study, we provide epidemiological assessment of ambient paraquat exposure and Parkinson's disease (PD) risk in a population-based study of PD in agricultural regions of Central California.

METHODS

Based on 829 PD patients and 824 community controls, we assessed associations between ambient paraquat dichloride exposure and PD. We estimated residential and workplace proximity to commercial agricultural applications in three California counties since 1974 using the CA pesticide use reporting (PUR) data and land use maps. We evaluated any, duration and average intensity [pounds (0.45 kilograms) per acre per year] of exposure for paraquat in four time windows.

RESULTS

Ambient paraquat exposure assessed at both residence and workplace was associated with PD, based on several different exposure measures. The PD patients both lived and worked near agricultural facilities applying greater amounts of the herbicide than community controls. For workplace proximity to commercial applications since 1974, working near paraquat applications every year in the window [odds ratio (OR) = 2.15, 95% confidence interval (CI) = 1.46, 3.19] and a higher average intensity of exposure [per 10 pounds (4.54 kilograms), OR = 2.08, 95% CI = 1.31, 3.38] were both associated with an increased odds of PD. Similar associations were observed for residential proximity (duration: OR = 1.91, 95% CI = 1.30, 2.83; average intensity: OR = 1.72, 95% CI = 0.99, 3.04). Risk estimates were comparable for men and women, and the strongest odds were observed for those diagnosed at ≤60 years of age.

CONCLUSION

This study provides further indication that paraquat dichloride exposure increases the risk of Parkinson's disease.

Untargeted serum metabolomics reveals novel metabolite associations and disruptions in amino acid and lipid metabolism in Parkinson's disease

BACKGROUND

Untargeted high-resolution metabolomic profiling provides simultaneous measurement of thousands of metabolites. Metabolic networks based on these data can help uncover disease-related perturbations across interconnected pathways.

OBJECTIVE

Identify metabolic disturbances associated with Parkinson's disease (PD) in two population-based studies using untargeted metabolomics.

METHODS

We performed a metabolome-wide association study (MWAS) of PD using serum-based untargeted metabolomics data derived from liquid chromatography with high-resolution mass spectrometry (LC-HRMS) using two distinct population-based case-control populations. We also combined our results with a previous publication of 34 metabolites linked to PD in a large-scale, untargeted MWAS to assess external validation.

RESULTS

LC-HRMS detected 4,762 metabolites for analysis (HILIC: 2716 metabolites; C18: 2046 metabolites). We identified 296 features associated with PD at FDR<0.05, 134 having a log2 fold change (FC) beyond ±0.5 (228 beyond ±0.25). Of these, 104 were independently associated with PD in both discovery and replication studies at p<0.05 (170 at p<0.10), while 27 were associated with levodopa-equivalent dose among the PD patients. Intriguingly, among the externally validated features were the microbial-related metabolites, p-cresol glucuronide (FC=2.52, 95% CI=1.67, 3.81, FDR=7.8e-04) and p-cresol sulfate. P-cresol glucuronide was also associated with motor symptoms among patients. Additional externally validated metabolites associated with PD include phenylacetyl-L-glutamine, trigonelline, kynurenine, biliverdin, and pantothenic acid. Novel associations include the anti-inflammatory metabolite itaconate (FC=0.79, 95% CI=0.73, 0.86; FDR=2.17E-06) and cysteine-S-sulfate (FC=1.56, 95% CI=1.39, 1.75; FDR=3.43E-11). Seventeen pathways were enriched, including several related to amino acid and lipid metabolism.

CONCLUSIONS

Our results revealed PD-associated metabolites, confirming several previous observations, including for p-cresol glucuronide, and newly implicating interesting metabolites, such as itaconate. Our data also suggests metabolic disturbances in amino acid and lipid metabolism and inflammatory processes in PD.

Ethnicity and Parkinson's Disease: Motor and Nonmotor Features and Disease Progression in Latino Patients Living in Rural California

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder among older adults worldwide. Currently, studies of PD progression rely primarily on White non-Latino (WNL) patients. Here, we compare clinical profiles and PD progression in Latino and WNL patients enrolled in a community-based study in rural Central California.

METHOD

PD patients within 5 years of diagnosis were identified from 3 counties between 2001 and 2015. During up to 3 visits, participants were examined by movement disorders specialists and interviewed. We analyzed cross-sectional differences in PD clinical features severity at each study visit and used linear mixed models and Cox proportional hazards models to compare motor, nonmotor, and disability progression longitudinally and to assess time to death in Latinos compared to WNL patients.

RESULTS

Of 775 patients included, 138 (18%) self-identified as Latino and presented with earlier age at diagnosis (63.6 vs 68.9) and death (78.6 vs 81.5) than WNL. Motor (hazard ratio [HR] = 1.17 [0.71, 1.94]) and nonmotor symptoms did not progress faster in Latino versus WNL patients after accounting for differences in baseline symptom severity. However, Latino patients progressed to disability stages according to Hoehn and Yahr faster than WNL (HR = 1.81 [1.11, 2.96]). Motor and nonmotor symptoms in Latino patients were also medically managed less well than in WNL.

CONCLUSIONS

Our PD study with a large proportion of Latino enrollees and progression data reveals disparities in clinical features and progression by ethnicity that may reflect healthcare access and structural socioeconomic disadvantages in Latino patients with PD.

A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides

Parkinson's disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative epidemiologic study of pesticide exposures and PD with toxicity screening in dopaminergic neurons derived from PD patient induced pluripotent stem cells (iPSCs) to identify Parkinson's-relevant pesticides. Agricultural records enable investigation of 288 specific pesticides and PD risk in a comprehensive, pesticide-wide association study. We associate long-term exposure to 53 pesticides with PD and identify co-exposure profiles. We then employ a live-cell imaging screening paradigm exposing dopaminergic neurons to 39 PD-associated pesticides. We find that 10 pesticides are directly toxic to these neurons. Further, we analyze pesticides typically used in combinations in cotton farming, demonstrating that co-exposures result in greater toxicity than any single pesticide. We find trifluralin is a driver of toxicity to dopaminergic neurons and leads to mitochondrial dysfunction. Our paradigm may prove useful to mechanistically dissect pesticide exposures implicated in PD risk and guide agricultural policy.

Proximity to residential and workplace pesticides application and the risk of progression of Parkinson's diseases in Central California

BACKGROUND

Pesticide exposure has consistently been associated with Parkinson's disease (PD) onset. Yet, fewer epidemiologic studies have examined whether pesticides influence PD motor and non-motor symptom progression.

OBJECTIVES

Using a geographic information system tool that integrates agricultural pesticide use reports and land use records to derive ambient exposures at residences and workplaces, we assessed associations between specific pesticides previously related to PD onset with PD symptom progression in two PD patient cohorts living in agricultural regions of California.

METHODS

We calculated the pounds of pesticide applied agriculturally near each participant's residential or occupational addresses from 1974 to the year of PD diagnosis, using a geographic information system tool that links the California Pesticide Use Reports database to land use data. We examined 53 pesticides selected a priori as they have previously been associated with PD onset. We longitudinally followed two PD patient cohorts (PEG1 N = 242, PEG2 N = 259) for an average of 5.0 years (SD ± 3.5) and 2.7 years (SD ± 1.6) respectively and assessed PD symptoms using the movement disorder specialist-administered Unified Parkinson's disease Rating Scale part III (UPDRS), Mini-Mental State Examination (MMSE), and Geriatric Depression Scale (GDS). Weighted time-to-event regression models were implemented to estimate effects.

RESULTS

Ten agricultural pesticides, including copper sulfate (pentahydrate), 2-methyl-4-chlorophenoxyacetic acid (MCPA) dimethylamine salt, tribufos, sodium cacodylate, methamidophos, ethephon, propargite, bromoxynil octanoate, monosodium methanearsonate (MSMA), and dicamba, were associated with faster symptom progression. Among these pesticides, residential or workplace proximity to higher amounts of copper sulfate (pentahydrate) and MCPA (dimethylamine salt) was associated with all three progression endpoints (copper sulfate: HRs = 1.22-1.36, 95 % CIs = 1.03-1.73; MCPA: HRs = 1.27-1.35, 95 % CIs = 1.02-1.70).

CONCLUSIONS

Our findings suggest that pesticide exposure may not only be relevant for PD onset but also PD progression phenotypes. We have implicated ten specific pesticide active ingredients in faster PD motor and non-motor decline.

Immune system disruptions implicated in whole blood epigenome-wide association study of depression among Parkinson's disease patients

Although Parkinson's Disease (PD) is typically described in terms of motor symptoms, depression is a common feature. We explored whether depression influences blood-based genome-wide DNA methylation (DNAm) in 692 subjects from a population-based PD case-control study, using both a history of clinically diagnosed depression and current depressive symptoms measured by the geriatric depression scale (GDS). While PD patients in general had more immune activation and more accelerated epigenetic immune system aging than controls, the patients experiencing current depressive symptoms (GDS≥5) showed even higher levels of both markers than patients without current depressive symptoms (GDS<5). For PD patients with a history of clinical depression compared to those without, we found no differences in immune cell composition. However, a history of clinical depression among patients was associated with differentially methylated CpGs. Epigenome-wide association analysis (EWAS) revealed 35 CpGs associated at an FDR≤0.05 (569 CpGs at FDR≤0.10, 1718 CpGs at FDR≤0.15). Gene set enrichment analysis implicated immune system pathways, including immunoregulatory interactions between lymphoid and non-lymphoid cells (p-adj = 0.003) and cytokine-cytokine receptor interaction (p-adj = 0.004). Based on functional genomics, 25 (71%) of the FDR≤0.05 CpGs were associated with genetic variation at 45 different methylation quantitative trait loci (meQTL). Twenty-six of the meQTLs were also expression QTLs (eQTLs) associated with the abundance of 53 transcripts in blood and 22 transcripts in brain (substantia nigra, putamen basal ganglia, or frontal cortex). Notably, cg15199181 was strongly related to rs823114 (SNP-CpG p-value = 3.27E-310), a SNP identified in a PD meta-GWAS and related to differential expression of PM20D1, RAB29, SLC41A1, and NUCKS1. The entire set of genes detected through functional genomics was most strongly overrepresented for interferon-gamma-mediated signaling pathway (enrichment ratio = 18.8, FDR = 4.4e-03) and T cell receptor signaling pathway (enrichment ratio = 13.2, FDR = 4.4e-03). Overall, the current study provides evidence of immune system involvement in depression among Parkinson's patients.

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Parkinson's disease (PD) is associated with clinical depression prior to PD onset and depressive symptoms after PD diagnosis.

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Epigenome-wide analysis revealed CpGs related to current depressive symptoms and a history of clinical depression among PD patients.

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Patients experiencing current depressive symptoms had the highest epigenetic-based neutrophil-to-lymphocyte ratio on average.

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Patients with a history of clinical depression had differentially methylated CpGs in genes enriched for immune system pathways.

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Many of the depression associated CpGs were linked to differential expression through meQTL/eQTLs, which included GWAS variants.

Stochastic Epigenetic Mutations Influence Parkinson's Disease Risk, Progression, and Mortality

BACKGROUND

Stochastic epigenetic mutations (SEM) reflect a deviation from normal site-specific methylation patterns. Epigenetic mutation load (EML) captures the accumulation of SEMs across an individual's genome and may reflect dysfunction of the epigenetic maintenance system in response to epigenetic challenges.

OBJECTIVE

We investigate whether EML is associated with PD risk and time to events (i.e., death and motor symptom decline).

METHODS

We employed logistic regression and Cox proportional hazards regression to assess the association between EML and several outcomes. Our analyses are based on 568 PD patients and 238 controls from the Parkinson's disease, Environment and Genes (PEG) study, for whom blood-based methylation data was available.

RESULTS

We found an association for PD onset and EML in all genes (OR = 1.90; 95%CI 1.52-2.37) and PD-related genes (OR = 1.87; 95%CI 1.50-2.32). EML was also associated with time to a minimum score of 35 points on the motor UPDRS exam (OR = 1.28; 95%CI 1.06-1.56) and time to death (OR = 1.29, 95%CI 1.11-1.49). An analysis of PD related genes only revealed five intragenic hotspots of high SEM density associated with PD risk.

CONCLUSION

Our findings suggest an enrichment of methylation dysregulation in PD patients in general and specifically in five PD related genes. EML may also be associated with time to death and motor symptom progression in PD patients.

Accelerated hematopoietic mitotic aging measured by DNA methylation, blood cell lineage, and Parkinson's disease

BACKGROUND

Aging and inflammation are important components of Parkinson's disease (PD) pathogenesis and both are associated with changes in hematopoiesis and blood cell composition. DNA methylation (DNAm) presents a mechanism to investigate inflammation, aging, and hematopoiesis in PD, using epigenetic mitotic aging and aging clocks. Here, we aimed to define the influence of blood cell lineage on epigenetic mitotic age and then investigate mitotic age acceleration with PD, while considering epigenetic age acceleration biomarkers.

RESULTS

We estimated epigenetic mitotic age using the "epiTOC" epigenetic mitotic clock in 10 different blood cell populations and in a population-based study of PD with whole-blood. Within subject analysis of the flow-sorted purified blood cell types DNAm showed a clear separation of epigenetic mitotic age by cell lineage, with the mitotic age significantly lower in myeloid versus lymphoid cells (p = 2.1e-11). PD status was strongly associated with accelerated epigenetic mitotic aging (AccelEpiTOC) after controlling for cell composition (OR = 2.11, 95 % CI = 1.56, 2.86, p = 1.6e-6). AccelEpiTOC was also positively correlated with extrinsic epigenetic age acceleration, a DNAm aging biomarker related to immune system aging (with cell composition adjustment: R = 0.27, p = 6.5e-14), and both were independently associated with PD. Among PD patients, AccelEpiTOC measured at baseline was also associated with longitudinal motor and cognitive symptom decline.

CONCLUSIONS

The current study presents a first look at epigenetic mitotic aging in PD and our findings suggest accelerated hematopoietic cell mitosis, possibly reflecting immune pathway imbalances, in early PD that may also be related to motor and cognitive progression.

Organophosphate Pesticide Exposures, Nitric Oxide Synthase Gene Variants, and Gene-Pesticide Interactions in a Case-Control Study of Parkinson's Disease, California (USA)

BACKGROUND

Nitric oxide synthase (NOS) genes are candidates for Parkinson's disease (PD) because NOS enzymes produce nitric oxide (NO), a pro-oxidant that can damage neurons. Widely used organophosphate (OP) pesticides can induce oxidative stress and are reported to increase PD risk. Additionally, two single nucleotide polymorphisms (SNPs) from the PON1 (paraoxonase 1) gene influence the ability to metabolize OPs.

OBJECTIVE

Here, we investigated contributions of NOS genes and OP pesticides to PD risk, controlling for PON1 status.

METHODS

In 357 incident PD cases and 495 population controls, we investigated eight NOS SNPs and interactions with both household and ambient agricultural OP exposures assessed with geographic information system (GIS).

RESULTS

In comparing PD in homozygous variant carriers of NOS2A rs1060826 versus homozygous wild-type or heterozygotes, we estimate an adjusted odds ratio (OR) of 1.51 (95% CI: 0.95, 2.41). When considering interactions between NOS1 rs2682826 and OP exposure from household use, the OR for frequent OP use alone was 1.30 (95% CI: 0.72, 2.34) and for the CT+TT genotype alone was 0.89 (95% CI: 0.58, 1.39), and for frequent OP use combined with the CT+TT genotype the OR was 2.84 (95% CI: 1.49, 5.40) (interaction p-value 0.04). Similar results were seen for ambient OP exposure. Interactions between OP exposure and three other NOS1 SNPs and a genetic risk score combining all NOS1 SNPs reached statistical significance.

CONCLUSIONS

We found that OP pesticides were more strongly associated with PD among participants with variant genotypes in NOS1, consistent with the importance of oxidative stress-inducing mechanisms. Our data provide evidence for NOS1 modifying PD risk in OP exposed populations.

CITATION

Paul KC, Sinsheimer JS, Rhodes SL, Cockburn M, Bronstein J, Ritz B. 2016. Organophosphate pesticide exposures, nitric oxide synthase gene variants, and gene-pesticide interactions in a case-control study of Parkinson's disease, California (USA). Environ Health Perspect 124:570-577; http://dx.doi.org/10.1289/ehp.1408976.

Common Genetic Variant Association with Altered HLA Expression, Synergy with Pyrethroid Exposure, and Risk for Parkinson's Disease: An Observational and Case-Control Study

Background:

The common noncoding single-nucleotide polymorphism (SNP) rs3129882 in HLA-DRA is associated with risk for idiopathic Parkinson’s disease (PD). The location of the SNP in the major histocompatibility complex class II (MHC-II) locus implicates regulation of antigen presentation as a potential mechanism by which immune responses link genetic susceptibility to environmental factors in conferring lifetime risk for PD.

Aims:

The aim of this study was to determine the effect of this SNP on the MHC-II locus and its synergy with pesticide exposure.

Methods:

For immunophenotyping, blood cells from 81 subjects were analyzed by quantitative reverse transcription-PCR and flow cytometry. A case–control study was performed on a separate cohort of 962 subjects to determine association of pesticide exposure and the SNP with risk of PD.

Results:

Homozygosity for G at this SNP was associated with heightened baseline expression and inducibility of MHC class II molecules in B cells and monocytes from peripheral blood of healthy controls and PD patients. In addition, exposure to a commonly used class of insecticide, pyrethroids, synergized with the risk conferred by this SNP (odds ratio=2.48, P=0.007), thereby identifying a novel gene–environment interaction that promotes risk for PD via alterations in immune responses.

Conclusions:

In sum, these novel findings suggest that the MHC-II locus may increase susceptibility to PD through presentation of pathogenic, immunodominant antigens and/or a shift toward a more pro-inflammatory CD4+ T-cell response in response to specific environmental exposures, such as pyrethroid exposure through genetic or epigenetic mechanisms that modulate MHC-II gene expression.

Head injury, α-synuclein genetic variability and Parkinson's disease

BACKGROUND AND PURPOSE

Head injury has been linked to Parkinson's disease (PD) in some but not all studies. Differences in the genetic and environmental susceptibility to PD between populations might be one explanation. The joint effects of head injuries and SNCA genetic variants were investigated.

METHODS

From 2001 to 2012, 561 incident idiopathic PD cases and 721 population controls from central California were enrolled. Subjects reported on head injuries throughout their lifetime and were assessed for genetic variability in the SNCA 5' region (D4S3481; Rep1) and 3' untranslated region (rs356165). In unconditional logistic regression models adjusted for confounders, interactions between head injuries and genetic risk variants were investigated.

RESULTS

Parkinson's disease risk in individuals with head injury who are carriers of at least one 263 bp allele in D4S3481 or rs356165 variants was 3-4.5-fold higher compared with non-carriers without head injuries. However, tests for interaction between head injury and SNCA D4S3481or rs356165 were not statistically significant.

CONCLUSIONS

Our study finds some evidence that head injury and D4S3481 or rs356165 variants jointly increase the risk of PD but little evidence of interaction.

Systematic review: efficacy and safety of medical marijuana in selected neurologic disorders: report of the Guideline Development Subcommittee of the American Academy of Neurology

OBJECTIVE

To determine the efficacy of medical marijuana in several neurologic conditions.

METHODS

We performed a systematic review of medical marijuana (1948-November 2013) to address treatment of symptoms of multiple sclerosis (MS), epilepsy, and movement disorders. We graded the studies according to the American Academy of Neurology classification scheme for therapeutic articles.

RESULTS

Thirty-four studies met inclusion criteria; 8 were rated as Class I.

CONCLUSIONS

The following were studied in patients with MS: (1) Spasticity: oral cannabis extract (OCE) is effective, and nabiximols and tetrahydrocannabinol (THC) are probably effective, for reducing patient-centered measures; it is possible both OCE and THC are effective for reducing both patient-centered and objective measures at 1 year. (2) Central pain or painful spasms (including spasticity-related pain, excluding neuropathic pain): OCE is effective; THC and nabiximols are probably effective. (3) Urinary dysfunction: nabiximols is probably effective for reducing bladder voids/day; THC and OCE are probably ineffective for reducing bladder complaints. (4) Tremor: THC and OCE are probably ineffective; nabiximols is possibly ineffective. (5) Other neurologic conditions: OCE is probably ineffective for treating levodopa-induced dyskinesias in patients with Parkinson disease. Oral cannabinoids are of unknown efficacy in non-chorea-related symptoms of Huntington disease, Tourette syndrome, cervical dystonia, and epilepsy. The risks and benefits of medical marijuana should be weighed carefully. Risk of serious adverse psychopathologic effects was nearly 1%. Comparative effectiveness of medical marijuana vs other therapies is unknown for these indications.

Job exposure matrix (JEM)-derived estimates of lifetime occupational pesticide exposure and the risk of Parkinson's disease

Studies that report an association between Parkinson's disease (PD) and occupational pesticide exposure often use self-reported exposure and none adjust for concomitant ambient pesticide exposure. For a population-based case-control study of PD conducted in California's heavily agricultural region, the authors developed a comprehensive job exposure matrix (JEM) to assess occupational exposure to pesticides. Relying on 357 incident cases and 750 population controls enrolled between 2001 and 2011, the authors estimated more than a 2-fold risk increase for PD among men classified as highly occupationally exposed. The authors also observed an exposure-response pattern and farming tasks with direct and intense pesticide exposures such as spraying and handling of pesticides resulted in greater risks than indirect bystander exposures. Results did not change after adjustment for ambient pesticide exposure. The authors provide further evidence that occupational pesticide exposure increases the risk of PD.

Functional paraoxonase 1 variants modify the risk of Parkinson's disease due to organophosphate exposure

BACKGROUND

We previously demonstrated that carriers of the "slower metabolizer" MM genotype of paraoxonase (PON1) who were also exposed to ambient organophosphate (OP) pesticides at their residences were at increased risk of developing Parkinson's disease (PD). Here, with a larger sample size, we extend our previous investigation to consider additional sources of ambient exposure and examined two additional functional PON1 variants.

METHODS

From 2001 to 2011, we enrolled incident cases of idiopathic PD and population controls living in central California. We genotyped three well-known functional PON1 SNPs: two exonic polymorphisms (PON1L55M and PON1Q192R) and the promoter region variant (PON1C-108T). Ambient exposures to diazinon, chlorpyrifos, and parathion at residential and workplace addresses were assessed using a validated geographic information system-based model incorporating records of agricultural pesticide applications in California.

RESULTS

The odds ratio (OR) for Caucasians exposed to OPs at either residential or workplace addresses varied by PON1 genotype; for exposed carriers of the "faster" metabolizer genotypes, ML or LL, we estimated lower odds ratios (range, 1.20-1.39) than for exposed carriers of the "slower" metabolizer genotype MM (range, 1.78-2.45) relative to unexposed carriers of the faster genotypes. We observed similarly increased ORs for exposure across PON1Q192R genotypes, but no differences across PON1C-108T genotypes. The largest ORs were estimated for exposed carriers of both PON1192QQ and PON155MM (OR range, 2.84-3.57).

CONCLUSIONS

Several functional PON1 variants may act together to modify PD risk for ambient OP exposures. While either PON1L55M or PON1Q192R may be sufficient to identify increased susceptibility, carriers of both slow metabolizer variants seem most susceptible to OP exposures.

Traumatic brain injury, paraquat exposure, and their relationship to Parkinson disease

OBJECTIVES

Traumatic brain injury (TBI) increased risk of Parkinson disease (PD) in many but not all epidemiologic studies, giving rise to speculations about modifying factors. A recent animal study suggested that the combination of TBI with subthreshold paraquat exposure increases dopaminergic neurodegeneration. The objective of our study was to investigate PD risk due to both TBI and paraquat exposure in humans.

METHODS

From 2001 to 2011, we enrolled 357 incident idiopathic PD cases and 754 population controls in central California. Study participants were asked to report all head injuries with loss of consciousness for >5 minutes. Paraquat exposure was assessed via a validated geographic information system (GIS) based on records of pesticide applications to agricultural crops in California since 1974. This GIS tool assesses ambient pesticide exposure within 500 m of residences and workplaces.

RESULTS

In logistic regression analyses, we observed a 2-fold increase in risk of PD for subjects who reported a TBI (adjusted odds ratio [AOR] 2.00, 95% confidence interval [CI] 1.28-3.14) and a weaker association for paraquat exposures (AOR 1.36, 95% CI 1.02-1.81). However, the risk of developing PD was 3-fold higher (AOR 3.01, 95% CI 1.51-6.01) in study participants with a TBI and exposure to paraquat than those exposed to neither risk factor.

CONCLUSIONS

While TBI and paraquat exposure each increase the risk of PD moderately, exposure to both factors almost tripled PD risk. These environmental factors seem to act together to increase PD risk in a more than additive manner.

α-Synuclein genetic variants predict faster motor symptom progression in idiopathic Parkinson disease

Currently, there are no reported genetic predictors of motor symptom progression in Parkinson's disease (PD). In familial PD, disease severity is associated with higher α-synuclein (SNCA) expression levels, and in postmortem studies expression varies with SNCA genetic variants. Furthermore, SNCA is a well-known risk factor for PD occurrence. We recruited Parkinson's patients from the communities of three central California counties to investigate the influence of SNCA genetic variants on motor symptom progression in idiopathic PD. We repeatedly assessed this cohort of patients over an average of 5.1 years for motor symptom changes employing the Unified Parkinson's Disease Rating Scale (UPDRS). Of 363 population-based incident PD cases diagnosed less than 3 years from baseline assessment, 242 cases were successfully re-contacted and 233 were re-examined at least once. Of subjects lost to follow-up, 69% were due to death. Adjusting for covariates, risk of faster decline of motor function as measured by annual increase in motor UPDRS exam score was increased 4-fold in carriers of the REP1 263bp promoter variant (OR 4.03, 95%CI:1.57-10.4). Our data also suggest a contribution to increased risk by the G-allele for rs356165 (OR 1.66; 95%CI:0.96-2.88), and we observed a strong trend across categories when both genetic variants were considered (p for trend = 0.002). Our population-based study has demonstrated that SNCA variants are strong predictors of faster motor decline in idiopathic PD. SNCA may be a promising target for therapies and may help identify patients who will benefit most from early interventions. This is the first study to link SNCA to motor symptom decline in a longitudinal progression study.

Medication responsiveness of motor symptoms in a population-based study of Parkinson disease

We assessed degree of Parkinson disease motor symptom improvement with medication among subjects enrolled in an ongoing, population-based study in Central California. The motor section of the unified Parkinson disease rating scale (UPDRS) was performed on subjects in both OFF and ON medication states, and difference between these scores was used as an indicator of symptomatic benefit. Higher OFF minus ON scores correlated with more severe baseline symptoms. There was equivalent improvement on the motor UPDRS scale for subjects divided according to medication classes used: levodopa alone 7.3 points, levodopa plus other medications 8.5 points, and dopamine agonists but not levodopa 6.1 points. In addition, there was no difference in the magnitude of improvement when subjects were divided according to Parkinson disease subtype, defined as tremor dominant, akinetic-rigid, or mixed. In this community-based sample, these values are within the range of a clinically important difference as defined by previous studies.

Parkinson's disease risk from ambient exposure to pesticides

Due to the heavy and expanding agricultural use of neurotoxic pesticides suspected to affect dopaminergic neurons, it is imperative to closely examine the role of pesticides in the development of Parkinson's disease (PD). We focus our investigation on pesticide use in California's heavily agricultural central valley by utilizing a unique pesticide use reporting system. From 2001 to 2007, we enrolled 362 incident PD cases and 341 controls living in the Central Valley of California. Employing our geographic information system model, we estimated ambient exposures to the pesticides ziram, maneb, and paraquat at work places and residences from 1974 to 1999. At workplaces, combined exposure to ziram, maneb, and paraquat increased risk of PD three-fold (OR: 3.09; 95% CI: 1.69, 5.64) and combined exposure to ziram and paraquat, excluding maneb exposure, was associated with a 80% increase in risk (OR:1.82; 95% CI: 1.03, 3.21). Risk estimates for ambient workplace exposure were greater than for exposures at residences and were especially high for younger onset PD patients and when exposed in both locations. Our study is the first to implicate ziram in PD etiology. Combined ambient exposure to ziram and paraquat as well as combined ambient exposure to maneb and paraquat at both workplaces and residences increased PD risk substantially. Those exposed to ziram, maneb, and paraquat together experienced the greatest increase in PD risk. Our results suggest that pesticides affecting different mechanisms that contribute to dopaminergic neuron death may act together to increase the risk of PD considerably.

α-Synuclein gene may interact with environmental factors in increasing risk of Parkinson's disease

BACKGROUND

Although of great interest and suggested in prior reports, possible α-synuclein (SNCA) gene-environment interactions have not been well investigated in humans.

METHODS

We used a population-based approach to examine whether the risk of Parkinson's disease (PD) depended on the combined presence of SNCA variations and two important environmental factors, pesticide exposures and smoking.

RESULTS/CONCLUSIONS

Similar to recent meta- and pooled analyses, our data suggest a lower PD risk in subjects who were either homozygous or heterozygous for the SNCA REP1 259 genotype, and a higher risk in subjects who were either homozygous or heterozygous for the REP1 263 genotype, especially among subjects with an age of onset ≤68 years. More importantly, while analyses of interactions were limited by small cell sizes, risk due to SNCA variations seemed to vary with pesticide exposure and smoking, especially in younger onset cases, suggesting an age-of-onset effect.

Familial associations of Alzheimer disease and essential tremor with Parkinson disease

BACKGROUND

We constructed a cohort of first-degree relatives of participants in a population-based case-control study of Parkinson disease (PD) and compared the occurrence of Alzheimer disease (AD) and essential tremor (ET) in relatives of PD cases and controls.

METHODS

We relied on proband interviews to assess family history in 372 probands with incident PD confirmed by a movement disorder specialist and 404 controls from three rural California counties.

RESULTS

Overall, for the 2980 first-degree relatives of PD cases, the risk of AD was not increased compared with the 2981 relatives of controls. But relatives of younger onset PD cases (<or=60 years of age) were three times more likely to have received an AD diagnosis [hazard ratios (HR): 2.86; 95%CI: 1.44, 5.71]. Our data also suggest that some relatives of PD probands might be at a slightly increased risk of receiving an ET diagnosis, especially relatives of tremor dominant cases (HR: 1.69; 95%CI 0.99, 2.88), younger onset cases (HR: 2.03; 95%CI 0.93, 4.44), and male relatives (HR: 2.31; 95%CI 1.13, 4.73). In addition, fathers of cases were almost 15 years younger than fathers of controls when diagnosed with ET. Results were stable in sensitivity analyses.

CONCLUSION

Our study suggests a familial susceptibility to AD amongst first-degree relatives of younger onset PD cases.

Well-water consumption and Parkinson's disease in rural California

INTRODUCTION

Investigators have hypothesized that consuming pesticide-contaminated well water plays a role in Parkinson's disease (PD), and several previous epidemiologic studies support this hypothesis.

OBJECTIVES

We investigated whether consuming water from private wells located in areas with documented historical pesticide use was associated with an increased risk of PD.

METHODS

We employed a geographic information system (GIS)-based model to estimate potential well-water contamination from agricultural pesticides among 368 cases and 341 population controls enrolled in the Parkinson's Environment and Genes Study (PEG). We separately examined 6 pesticides (diazinon, chlorpyrifos, propargite, paraquat, dimethoate, and methomyl) from among 26 chemicals selected for their potential to pollute groundwater or for their interest in PD, and because at least 10% of our population was exposed to them.

RESULTS

Cases were more likely to have consumed private well water and to have consumed it on average 4.3 years longer than controls (p = 0.02). High levels of possible well-water contamination with methomyl [odds ratio (OR) = 1.67; 95% confidence interval (CI), 1.00-2.78]), chlorpyrifos (OR = 1.87; 95% CI, 1.05-3.31), and propargite (OR = 1.92; 95% CI, 1.15-3.20) resulted in approximately 70-90% increases in relative risk of PD. Adjusting for ambient pesticide exposures only slightly attenuated these increases. Exposure to a higher number of water-soluble pesticides and organophosphate pesticides also increased the relative risk of PD.

CONCLUSION

Our study, the first to use agricultural pesticide application records, adds evidence that consuming well water presumably contaminated with pesticides may play a role in the etiology of PD.

Pathologic findings in retinal pigment epithelial cell implantation for Parkinson disease

BACKGROUND

Attempts at cell-based dopamine replacement therapy in Parkinson disease (PD) have included surgical implantation of adrenal medullary, fetal mesencephalic, and cultured human mesencephalic tissue grafts. Trials involving putamenal implantation of human retinal pigment epithelial (RPE) cells in PD have also been performed. Neuropathologic findings in humans undergoing RPE cell implantation have not heretofore been reported. We describe the brain autopsy findings from a subject enrolled in a clinical trial of RPE cells in gelatin microcarriers for treatment of PD, and suggest factors which may have impacted cell survival.

METHODS

A 68-year-old man underwent bilateral surgical implantation of 325,000 RPE cells in gelatin microcarriers (Spheramine) but died 6 months after surgery. The left cerebral hemisphere was examined. Routine postmortem formalin fixation was performed and standard, as well as immunohistochemical methods used to highlight senile plaque and Lewy body pathologic changes, iron deposition, cellular inflammation, and reactive astrocytosis in implant regions. Manual cell counts were done of RPE cells.

RESULTS

Hematoxylin-eosin and alpha-synuclein immunostains confirmed the diagnosis of PD. Needle tracts with matrix material and RPE cells were observed in the context of local inflammatory and astrocytic reactive change. A total of 118 cells were counted (estimated 0.036% survival).

CONCLUSIONS

Retinal pigment epithelial cells are seen in human brain 6 months postimplantation, but overall survival of implanted cells appeared poor.

Dopamine transporter genetic variants and pesticides in Parkinson's disease

BACKGROUND

Research suggests that independent and joint effects of genetic variability in the dopamine transporter (DAT) locus and pesticides may influence Parkinson's disease (PD) risk.

METHODS

In 324 incident PD patients and 334 population controls from our rural California case-control study, we genotyped rs2652510, rs2550956 (for the DAT 5' clades), and the 3' variable number of tandem repeats (VNTR). Using geographic information system methods, we determined residential exposure to agricultural maneb and paraquat applications. We also collected occupational pesticide use data. Employing logistic regression, we calculated odds ratios (ORs) for clade diplotypes, VNTR genotype, and number of susceptibility (A clade and 9-repeat) alleles and assessed susceptibility allele-pesticide interactions.

RESULTS

PD risk was increased separately in DAT A clade diplotype carriers [AA vs. BB: OR = 1.66; 95% confidence interval (CI), 1.08-2.57] and 3' VNTR 9/9 carriers (9/9 vs. 10/10: OR = 1.8; 95% CI, 0.96-3.57), and our data suggest a gene dosing effect. Importantly, high exposure to paraquat and maneb in carriers of one susceptibility allele increased PD risk 3-fold (OR = 2.99; 95% CI, 0.88-10.2), and in carriers of two or more alleles more than 4-fold (OR = 4.53; 95% CI, 1.70-12.1). We obtained similar results for occupational pesticide measures.

DISCUSSION

Using two independent pesticide measures, we a) replicated previously reported gene-environment interactions between DAT genetic variants and occupational pesticide exposure in men and b) overcame previous limitations of nonspecific pesticide measures and potential recall bias by employing state records and computer models to estimate residential pesticide exposure.

CONCLUSION

Our results suggest that DAT genetic variability and pesticide exposure interact to increase PD risk.

Parkinson's disease and residential exposure to maneb and paraquat from agricultural applications in the central valley of California

Evidence from animal and cell models suggests that pesticides cause a neurodegenerative process leading to Parkinson's disease (PD). Human data are insufficient to support this claim for any specific pesticide, largely because of challenges in exposure assessment. The authors developed and validated an exposure assessment tool based on geographic information systems that integrated information from California Pesticide Use Reports and land-use maps to estimate historical exposure to agricultural pesticides in the residential environment. In 1998-2007, the authors enrolled 368 incident PD cases and 341 population controls from the Central Valley of California in a case-control study. They generated estimates for maneb and paraquat exposures incurred between 1974 and 1999. Exposure to both pesticides within 500 m of the home increased PD risk by 75% (95% confidence interval (CI): 1.13, 2.73). Persons aged < or =60 years at the time of diagnosis were at much higher risk when exposed to either maneb or paraquat alone (odds ratio = 2.27, 95% CI: 0.91, 5.70) or to both pesticides in combination (odds ratio = 4.17, 95% CI: 1.15, 15.16) in 1974-1989. This study provides evidence that exposure to a combination of maneb and paraquat increases PD risk, particularly in younger subjects and/or when exposure occurs at younger ages.

Bilateral deep brain stimulation vs best medical therapy for patients with advanced Parkinson disease: a randomized controlled trial

CONTEXT

Deep brain stimulation is an accepted treatment for advanced Parkinson disease (PD), although there are few randomized trials comparing treatments, and most studies exclude older patients.

OBJECTIVE

To compare 6-month outcomes for patients with PD who received deep brain stimulation or best medical therapy.

DESIGN, SETTING, AND PATIENTS

Randomized controlled trial of patients who received either deep brain stimulation or best medical therapy, stratified by study site and patient age (< 70 years vs > or = 70 years) at 7 Veterans Affairs and 6 university hospitals between May 2002 and October 2005. A total of 255 patients with PD (Hoehn and Yahr stage > or = 2 while not taking medications) were enrolled; 25% were aged 70 years or older. The final 6-month follow-up visit occurred in May 2006.

INTERVENTION

Bilateral deep brain stimulation of the subthalamic nucleus (n = 60) or globus pallidus (n = 61). Patients receiving best medical therapy (n = 134) were actively managed by movement disorder neurologists.

MAIN OUTCOME MEASURES

The primary outcome was time spent in the "on" state (good motor control with unimpeded motor function) without troubling dyskinesia, using motor diaries. Other outcomes included motor function, quality of life, neurocognitive function, and adverse events.

RESULTS

Patients who received deep brain stimulation gained a mean of 4.6 h/d of on time without troubling dyskinesia compared with 0 h/d for patients who received best medical therapy (between group mean difference, 4.5 h/d [95% CI, 3.7-5.4 h/d]; P < .001). Motor function improved significantly (P < .001) with deep brain stimulation vs best medical therapy, such that 71% of deep brain stimulation patients and 32% of best medical therapy patients experienced clinically meaningful motor function improvements (> or = 5 points). Compared with the best medical therapy group, the deep brain stimulation group experienced significant improvements in the summary measure of quality of life and on 7 of 8 PD quality-of-life scores (P < .001). Neurocognitive testing revealed small decrements in some areas of information processing for patients receiving deep brain stimulation vs best medical therapy. At least 1 serious adverse event occurred in 49 deep brain stimulation patients and 15 best medical therapy patients (P < .001), including 39 adverse events related to the surgical procedure and 1 death secondary to cerebral hemorrhage.

CONCLUSION

In this randomized controlled trial of patients with advanced PD, deep brain stimulation was more effective than best medical therapy in improving on time without troubling dyskinesias, motor function, and quality of life at 6 months, but was associated with an increased risk of serious adverse events.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00056563.

Meeting report: consensus statement-Parkinson's disease and the environment: collaborative on health and the environment and Parkinson's Action Network (CHE PAN) conference 26-28 June 2007

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder. People with PD, their families, scientists, health care providers, and the general public are increasingly interested in identifying environmental contributors to PD risk.

METHODS

In June 2007, a multidisciplinary group of experts gathered in Sunnyvale, California, USA, to assess what is known about the contribution of environmental factors to PD.

RESULTS

We describe the conclusions around which they came to consensus with respect to environmental contributors to PD risk. We conclude with a brief summary of research needs.

CONCLUSIONS

PD is a complex disorder, and multiple different pathogenic pathways and mechanisms can ultimately lead to PD. Within the individual there are many determinants of PD risk, and within populations, the causes of PD are heterogeneous. Although rare recognized genetic mutations are sufficient to cause PD, these account for < 10% of PD in the U.S. population, and incomplete penetrance suggests that environmental factors may be involved. Indeed, interplay among environmental factors and genetic makeup likely influences the risk of developing PD. There is a need for further understanding of how risk factors interact, and studying PD is likely to increase understanding of other neurodegenerative disorders.

K+ channel KV3.1 associates with OSP/claudin-11 and regulates oligodendrocyte development

K(+) channels are differentially expressed throughout oligodendrocyte (Olg) development. K(V)1 family voltage-sensitive K(+) channels have been implicated in proliferation and migration of Olg progenitor cell (OPC) stage, and inward rectifier K+ channels (K(IR))4.1 are required for OPC differentiation to myelin-forming Olg. In this report we have identified a Shaw family K(+) channel, K(V)3.1, that is involved in proliferation and migration of OPC and axon myelination. Application of anti-K(V)3.1 antibody or knockout of Kv3.1 gene decreased the sustained K(+) current component of OPC by 50% and 75%, respectively. In functional assays block of K(V)3.1-specific currents or knockout of Kv3.1 gene inhibited proliferation and migration of OPC. Adult Kv3.1 gene-knockout mice had decreased diameter of axons and decreased thickness of myelin in optic nerves compared with age-matched wild-type littermates. Additionally, K(V)3.1 was identified as an associated protein of Olg-specific protein (OSP)/claudin-11 via yeast two-hybrid analysis, which was confirmed by coimmunoprecipitation and coimmunohistochemistry. In summary, the K(V)3.1 K(+) current accounts for a significant component of the total K(+) current in cells of the Olg lineage and, in association with OSP/claudin-11, plays a significant role in OPC proliferation and migration and myelination of axons.

The impact of thalamic stimulation on activities of daily living for essential tremor

BACKGROUND

Deep Brain Stimulation (DBS) of the ventro-intermedius nucleus of the thalamus is the treatment of choice for drug-refractory essential tremor (ET). This study evaluated the effectiveness of thalamic stimulation in improving the patient's quality of life through activities of daily living.

METHODS

Sixteen ET patients completed a health questionnaire, the "Tremor Activities of Daily Living Scale" (TADLS) measured by the patient, a 10-item subset of the TADLS measured by the clinician, and the Fahn-Tolosa-Marin tremor rating scale (TRS). Each patient was evaluated with the stimulator on and off with the average evaluation occurring 13 months after surgery. Additionally, improvements on the TADLS were compared to electrode positioning on the axial plane and stimulation parameters.

RESULTS

There was a 44.0% improvement in the patient-rated TADLS, a 45.2% improvement in the clinician-rated TADLS, and a 33.9% improvement in the TRS. The average electrode location was 5.65 mm anterior to the posterior commissure (AC-PC), 13.4 mm lateral from the midline, and 2.0 mm below the AC-PC line. The average stimulation parameters were 2.74 Volts, 160 Hertz, and 119 microsec. There was no correlation between improvements on the TADLS, electrode location, and stimulation parameters. Of the 16 patients, 10 patients would repeat the surgery, two were unsure, and four would not repeat the surgery.

CONCLUSIONS

Tremor is significantly controlled with DBS and activities of daily living are highly correlated with patient satisfaction. The degree of improvement in the four patients who would not repeat the surgery was outweighed by the negative factors associated with the surgery.

Utilization of dental sealants by Alabama Medicaid children: barriers in meeting the year 2010 objectives

PURPOSE

As a national objective, 50% of US children are expected to have dental sealants on at least one permanent molar by the age of 14 years. The present study was conducted to estimate the prevalence of dental sealants among Alabama Medicaid children and to evaluate the characteristics of the sealant users and non-users so the potential barriers in meeting the year 2000/2010 sealant objectives can be identified.

METHODS

Alabama Medicaid 1990-1997 claims for children (N = 3,683,842) were analyzed using basic descriptive statistics, likelihood ratio, Chi-Square and t-tests, and ANOVA. Logistic regression analysis was used in identifying the predictors of dental sealant utilization.

RESULTS

Nearly 22 percent of children had at least one sealant claim by 12 to 14 years of age (white = 28.3%; Black = 19.8%; OR = 1.6, 95% CI = 1.4-1.8; female = 23.6%; male = 19.7%; OR = 1.3, 95% CI = 1.1-1.4). 5- to 9-year-olds were more likely to have sealants compared to 11- to 14-year-olds (OR = 4.1, 95% CI = 2.7-6.1). The availability of a Medicaid accepting dentist within the county of residence was a significant predictor (OR = 1.5, 95% CI = 1.1-2.2). Less than 2% of the annual amount claimed for total dental services in Alabama was related to sealants and the providers were reimbursed only for 50% to 70% of the amount claimed for sealant procedures.

CONCLUSIONS

Racial and gender disparities in obtaining care, non-availability of a Medicaid-participating dentist within the county, and lower payment/claim ratio may make the national sealant objective difficult to achieve in Alabama.

Estimation of neonatal outcome and perinatal therapy use

OBJECTIVES

To learn whether US obstetricians and pediatricians accurately estimate rates of survival and freedom from handicap in preterm infants and to learn whether their knowledge and attitudes influence their choice of interventions that may enhance survival.

METHODS

A cross-sectional survey of obstetricians and pediatricians practicing in the United States was performed using a pretested questionnaire designed to identify their knowledge regarding survival and handicap-free rates of infants born at 23 to 36 weeks of gestation. At each week of gestation, they were asked whether they would provide specific therapeutic interventions to either the expectant mother or infant. Survival and handicap-free rates were compared with published national rates. Obstetricians and pediatricians were divided into an optimists group and a pessimists group, based on their estimates of survival. The rates at which each group used therapeutic interventions were compared.

RESULTS

Both obstetricians and pediatricians underestimated survival rates from 24 through 35 weeks of gestation and freedom from serious handicap from 23 through 36 weeks of gestation. On the average, optimists accurately predicted neonatal survival. Obstetricians who underestimated neonatal survival would less often administer antenatal corticosteroids, perform a cesarean section for fetal distress, and transfer a mother to a tertiary center. Pediatricians who underestimated neonatal survival would less often use mechanical ventilation, cardiopulmonary resuscitation, inotropes, intravenous fluids, thermal support, and oxygen supplementation.

CONCLUSION

Physicians underestimate survival and freedom from handicap in preterm infants. Underestimation of outcome is associated with restriction in the use of appropriate interventions.

Low prenatal weight gain among adult WIC participants delivering term singleton infants: variation by maternal and program participation characteristics

OBJECTIVE

To determine the association of maternal and prenatal WIC program participation characteristics with low prenatal weight gain among adult women delivering liveborn, singleton infants at term.

METHODS

WIC program data for 19,017 Black and White Alabama women delivering in 1994 were linked with birth certificate files to examine the association of anthropometric, demographic, reproductive, hematologic, behavioral and program participation characteristics with low prenatal weight gain.

RESULTS

One third (31.0%) had low prenatal weight gain as defined by the Institute of Medicine. The incidence of low weight gain was increased among women who had < 12 years of education, were single, Black, anemic, had low or normal prepregnancy body mass index (BMI), increased parity, interpregnancy intervals < or = 24 months, used tobacco or alcohol, or entered prenatal care or WIC programs after the first trimester. After adjusting for selected maternal characteristics, the adjusted odds ratios (AOR) for low weight gain were increased with short interpregnancy intervals (AOR 1.21 to 2.20); tobacco use (AOR 1.16 to 1.40), anemia (AOR 1.20 to 1.25), and second trimester entry into prenatal care (AOR 1.14 to 1.20); the size of the AORs and 95% confidence intervals varied by BMI and racial subgroup.

CONCLUSIONS

The results of this study suggest that WIC interventions targeting low prenatal weight gain be focused on risk factors present not only during pregnancy, but during the pre- and interconceptional periods as well. Interventions should target low BMI, tobacco use, and anemia, and include attention to nutrition screening and risk reduction among women in postpartum and family planning clinic settings.

Estimation of outcome and restriction of interventions in neonates

OBJECTIVE

To learn whether pediatricians accurately estimate rates of survival and freedom from handicap in preterm infants and to learn whether their knowledge and attitude influence their choice of interventions that may enhance survival of extremely preterm infants.

METHODS

Pediatricians practicing in Alabama were surveyed using a pretested questionnaire designed to identify pediatricians' knowledge regarding survival and handicap-free rates of infants born at gestational ages between 21 and 36 weeks. For infants born at each week of gestation, they were asked if they would provide specific therapeutic interventions. Survival and handicap-free rates were compared with published national rates. Pediatricians were divided into an optimist group and a pessimist group based on how their estimates of survival compared with national published data. The rates at which each group used therapeutic interventions were compared.

RESULTS

The 159 (57%) responding pediatricians underestimated survival rates from 23 through 34 weeks' gestation and freedom from serious handicap from 23 through 36 weeks. Responses of the optimists approximated actual data whereas the pessimists underestimated neonatal outcome. Those pediatricians who underestimated neonatal outcome would intervene less often with invasive therapies, including mechanical ventilation, cardiopulmonary resuscitation, inotropes, and intravenous fluids, compared with those who accurately predicted outcome from 23 through 27 weeks' gestation.

CONCLUSION

Pediatricians often underestimate neonatal outcome of preterm infants. Appropriate neonatal practice may be affected by this underestimation of the survival potential of preterm infants.

Interferon-gamma and monoclonal antibody 131I-labeled CC49: outcomes in patients with androgen-independent prostate cancer

To assess the tumor targeting, safety, and efficacy of monoclonal antibody 131I-labeled CC49 in patients with androgen-independent prostate cancer, 16 patients received 75 mCi/m2 of the radiolabeled antibody after 7 days of IFN-gamma pretreatment. Sequential tumor biopsies in three patients showed a median 5-fold (range, 2-6-fold) increase in the proportion of cells staining positively for the TAG-72 antigen, whereas one showed a decrease in staining. Fourteen patients received 131I-labeled CC49, whereas 2 showed a disease-related decrease in performance status, precluding antibody treatment. The antibody localized to sites of metastatic androgen-independent prostate cancer in 86% (12 of 14; 95% confidence interval, 57-95%) of cases. Both osseous and extraosseous sites were visualized, and in six (42%) patients, more areas were visible when the radioimmunoconjugate was used than were apparent when conventional scanning techniques were used. The localization of the conjugate in the marrow cavity was usually a site not visualized by the radionuclide bone scan, in which the isotope localizes primarily to the tumor-bone interface. The dose-limiting toxicity was thrombocytopenia because five (36%) patients showed grade IV and seven (50%) showed grade III effects. In addition, six (42%) patients, four of whom were hospitalized, showed a flare in baseline pain, and four showed a decrease in pain. No patient showed a >50% decline in prostate-specific antigen, although radionuclide bone scans remained stable in four cases for a median of 4 months. The results are consistent with dosimetry estimates showing that the delivered dose to tumor was subtherapeutic and suggest that approaches that exclusively target the bone tumor interface or the marrow stroma may be unable to completely eradicate disease in the marrow cavity. For CC49, improving outcomes would require repetitive dosing, which was precluded by the rapid development of a human antimouse antibody response.

Delayed internal capsule infarctions following radiofrequency pallidotomy. Report of three cases

The authors report on a series of patients with idiopathic Parkinson's disease (IPD) who underwent stereotactic radiofrequency (RF) pallidotomies, three of whom suffered delayed postoperative strokes. These three belonged to a group consisting of 42 patients with medically intractable IPD in whom 50 pallidotomies were performed. All three patients had significant previous vascular disease and were in a high-risk group for cerebral infarction. A postoperative magnetic resonance (MR) image was obtained immediately after the pallidotomy was performed to document the placement of the RF lesion and to rule out any hematoma. The delayed strokes occurred on postoperative Days 10, 51, and 117 in patients with previous vascular disease (Group 1, 11 patients). No strokes occurred in the group with the vascular disease risk factor (Group 2, 11 patients) or in the group with no risk factors for vascular disease (Group 3, 20 patients). This observation is statistically significant (p < 0.05). The T2-weighted MR images showed the lesions as high-intensity signals extending to the posterior limb of the internal capsule ipsilateral to the pallidotomy site. The poststroke T1-weighted images obtained in two patients showed persistent contrast enhancement of the RF lesion and no enhancement around the stroke lesion. Clinically and radiographically, these discrete new lesions represent delayed infarctions, suggesting that RF lesioning can induce delayed injury in adjacent tissue. Patients with previously identified vasculopathy may be at risk for delayed capsular infarction following RF pallidotomy.

Physician opinions of preterm infant outcome and their effect on antenatal corticosteroid use

Our purpose was to compare physician opinions about the appropriate use of corticosteroids with physician perceptions of preterm infant outcome. A total of 409 obstetricians and family physicians who provide maternity care in Alabama were surveyed to determine whether (and how) their perceptions of preterm infant outcome influenced their decision to use antenatal corticosteroids. Results were compared with those of a similar survey of Alabama physicians conducted in 1979. A total of 85% of physicians in 1992 versus 61% in 1979 reported that situations existed in which they would prescribe antenatal corticosteroids (p < 0.001). In 1992 physicians who underestimated preterm infant survival began corticosteroid use at later gestational ages than those physicians who did not underestimate survival (p < 0.02). In addition, 54% of physicians who underestimated preterm infant survival reported giving corticosteroids between 23 and 28 weeks' gestational age versus 73% of physicians with more accurate perceptions (p < 0.03). We conclude that in 1992, compared within 1979, more Alabama physicians reported antenatal corticosteroid use. Use of this treatment was influenced by each physician's perceptions of the probable outcome of the preterm infant.

Pharmacists as HIV/AIDS information resources: survey of Alabama pharmacists

Alabama pharmacists were surveyed by researchers from the University of Alabama at Birmingham's School of Public Health in collaboration with investigators at the Schools of Pharmacy at Auburn University and Stamford University as part of a statewide pharmacists' demonstration project to mobilize pharmacists and pharmacy locations as information resources for HIV/AIDS education and prevention. The objectives of the survey were to: (1) establish a baseline of knowledge and attitudes among Alabama pharmacists about HIV/AIDS; (2) to assess Alabama pharmacists' willingness to assume the role of HIV/AIDS information resources in their communities; and (3) to identify perceived barriers to assuming the role of information resources. The results of the survey were used in the development of an educational intervention program and will be used subsequently to assess the impact of the implementation of the Alabama demonstration project. Findings from this project will serve as a basis for development of a nationwide project as part of a collaborative agreement between the Centers for Disease Control and Prevention's National Partnership Program and the Foundation of Pharmacists and Corporate America for AIDS Education.

Comparison of perceived and actual rates of survival and freedom from handicap in premature infants

OBJECTIVE

Our goal was to learn whether physicians delivering obstetric care accurately estimated rates of survival and freedom from handicap in premature infants.

STUDY DESIGN

We surveyed by mail 409 obstetricians and general and family physicians reported to perform deliveries in Alabama to identify their perceptions regarding survival and handicap-free rates of infants born at gestational ages between 23 and 36 weeks, inclusive. Responses were compared with published national rates of survival and freedom from handicap by means of unpaired t tests.

RESULTS

A total of 224 physicians responded (55%), and 183 were still practicing obstetrics. They significantly underestimated survival rates from 23 through 34 weeks' gestation (p < 0.05) and freedom from serious handicap from 23 through 36 weeks' gestation (p < 0.05). They advocated early treatment of preterm labor, but < 50% would perform cesarean delivery for fetal distress before 26 weeks' gestation.

CONCLUSION

We conclude that physicians delivering obstetric care significantly underestimate survival and freedom from handicap in preterm infants. Perinatal care may be adversely affected by these misperceptions.

Bed rest in pregnancy

OBJECTIVE

To summarize existing data about the effectiveness of bed rest when used to improve various pregnancy outcomes and to determine how often bed rest is used and the cost associated with its use.

DATA SOURCES

We used the MEDLINE data base to search for all English language papers evaluating the effectiveness of bed rest in pregnancy. We also reviewed a number of textbooks and the 1988 National Infant Mortality Survey.

METHODS OF STUDY SELECTION

We reviewed these sources for recommendations about using bed rest in various obstetric conditions. We used the 1988 National Infant Mortality Survey to determine how often bed rest was used either to prevent or to treat various obstetric conditions and estimated the costs associated with its use.

DATA EXTRACTION AND SYNTHESIS

Bed rest is used in nearly 20% of all pregnancies to prevent or treat a wide variety of conditions, including spontaneous abortion, preterm labor, fetal growth retardation, edema, chronic hypertension, and preeclampsia. There is little evidence of effectiveness. The estimated costs associated with bed rest, including hospitalization, lost wages, and lost domestic productivity, range from more than $250 million to billions of dollars per year.

CONCLUSIONS

Bed rest is used extensively to treat a wide variety of pregnancy conditions, at substantial cost but with little proof of effectiveness. We recommend that because this intervention has failed the test of effectiveness, its use during pregnancy should be curtailed unless randomized trials demonstrate improvement in a specific outcome.

Dark-induced changes in activity and compartmentalization of retinal calmodulin kinase in the rat

Calmodulin kinase (CaM kinase) activity and immunoreactivity were measured in the cytosol and crude synaptic membranes of light- and dark-adapted rat retinas. Dark adaptation increased the calcium-independent CaM kinase activity 2.7 times and calcium-stimulated activity 3.9 times in membrane fractions. Dark adaptation also increased membrane-bound CaM kinase immunoreactivity 2.4 times. In the cytosol, dark adaptation increased calcium- and calmodulin-independent kinase activity 3.3-fold but did not enhance calcium- and calmodulin-dependent activity. Soluble CaM kinase immunoreactivity was decreased by 13% by dark exposure. These changes in enzyme activity and immunoreactivity are likely due to changes in the endogenous state of autophosphorylation and compartmental concentrations of CaM kinase and may represent translocation of CaM kinase from cytosol to membranes. CaM kinase may have an important role in modulating visual processes.

Decreased calmodulin kinase activity after status epilepticus

Status epilepticus was induced in paralyzed, ventilated rats using bicuculline and was maintained for 50 to 120 minutes. Cerebral cortex, hippocampus, and cerebellum were assayed for calmodulin kinase II activity in vitro using [gamma-32P]ATP and polyacrylamide gel electrophoresis. Seizures resulted in a 3.2 fold decrease in calmodulin kinase activity in crude synaptic membranes of cortex and in a 8.2 fold decrease in hippocampal membranes. Cytosolic calmodulin kinase activity was slightly increased in rats in status epilepticus but statistical significance was not reached. Status epilepticus did not affect calcium/calmodulin-dependent kinase activity in cerebellar membranes or cytosol. These data suggest that intense firing associated with continuous seizure activity decreases calmodulin kinase activity in cortical and hippocampal synaptic membranes, which may result in altered neuronal excitability.