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    <recommendedItem id="20100101_19_425"
                     title="AAN: Industrial Cleaner Again Tied to Parkinson Risk (CME/CE)"
                     score="0.012"
                     href="http://www.medpagetoday.com/MeetingCoverage/AAN/tb/18338?impressionId=1265800831207"
                     
      TORONTO  --  The degreasing agent trichloroethylene (TCE) has been linked to increased rates of Parkinson&apos;s disease among industrial workers in yet another study, this time involving a large, well-studied group of World War II veterans.&lt;br&gt;
&lt;br&gt;Parkinson&apos;s disease developed in individuals with occupational exposure to TCE at more than five times the rate seen in those without such exposure (odds ratio 5.5, 95% CI 1.02 to 30), reported Samuel Goldman, MD, of the Parkinson&apos;s Institute in Sunnyvale, Calif.&lt;br&gt;
&lt;br&gt;Goldman described the research in a phone interview with &lt;em&gt;MedPage Today&lt;/em&gt;. It&apos;s scheduled for presentation here in April at the American Academy of Neurology&apos;s annual meeting.&lt;br&gt;
&lt;br&gt;A previous study in 2008 had fingered TCE as the most likely culprit behind a cluster of Parkinson&apos;s disease cases afflicting workers at a single industrial plant. (See &lt;a href=&quot;http://www.medpagetoday.com/Geriatrics/ParkinsonsDisease/7894&quot; mce_href=&quot;http://www.medpagetoday.com/Geriatrics/ParkinsonsDisease/7894&quot; target=&quot;_blank&quot;&gt;Trichloroethylene Implicated as Risk for Parkinsonism&lt;/a&gt;)&lt;p&gt;&lt;/p&gt;
&lt;p&gt;Also, Goldman said, animal studies have found that TCE is selectively toxic to nigral dopaminergic neurons, the same type of nerve cell that progressively dies off in Parkinson&apos;s disease. He said the chemical&apos;s activity in rodent brains is very similar to that of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), a dopaminergic neurotoxin commonly used to simulate Parkinson&apos;s disease in preclinical research.&lt;/p&gt;
&lt;p&gt;Goldman said the new study was the first population-based analysis to link TCE to the disease.&lt;/p&gt;
&lt;p&gt;It focused on 198 twin pairs in the National Academy of Sciences-National Research Council&apos;s World War II Twins Cohort, which comprises some 16,000 twin pairs overall.&lt;/p&gt;
&lt;p&gt;Members of the all-male cohort, who were born from 1917 to 1927 and served in the war, have been followed since the 1960s. Occupational histories for participants are available along with medical records from the VA healthcare system.&lt;/p&gt;
&lt;p&gt;In those pairs chosen for the current study, records showed that one twin had developed Parkinson&apos;s disease and the other had not. This design largely eliminates genetics as a confounding factor in the analysis.&lt;/p&gt;
&lt;p&gt;Goldman explained that occupational histories for each participant were reviewed by a blinded industrial hygienist and a preventive medicine physician to identify likely exposures to TCE and four other industrial chemicals: xylene, toluene, carbon tetrachloride, and tetrachloroethylene.&lt;/p&gt;
&lt;p&gt;As a single source of exposure, only TCE was significantly associated with development of Parkinson&apos;s disease, Goldman said.&lt;/p&gt;
&lt;p&gt;People working as aircraft mechanics, machinists, plumbers, and electricians likely had regular exposure to TCE, Goldman said. The chemical was commonly used as a &quot;spot&quot; cleaner to remove grease and oils from metal surfaces. It was also used for a time as a dry cleaning solvent, although tetrachloroethylene was more common for that purpose.&lt;/p&gt;
&lt;p&gt;Goldman said no increased risk was seen with xylene or toluene, but there were near-significant trends toward increased Parkinson&apos;s disease risk from carbon tetrachloride and tetrachloroethylene: &lt;ul&gt; &lt;li&gt;Carbon tetrachloride: OR 2.8 (95% CI 0.97 to 7.8)&lt;/li&gt; &lt;li&gt;Tetrachloroethylene: OR 9.0 (95% CI 0.78 to 103)&lt;/li&gt; &lt;/ul&gt;&lt;/p&gt;
&lt;p&gt;Twins exposed to either TCE or tetrachloroethylene were at significantly increased risk, with an odds ratio of 8.1 (95% CI 1.43 to 43) relative to individuals with no exposure to either chemical.&lt;/p&gt;
&lt;p&gt;Goldman said the analysis also examined whether duration of exposure was associated with increased risk. He said the results were in the same pattern as for the yes-no exposure analysis, but the findings were very uncertain because of the relatively small sample size.&lt;/p&gt;
&lt;p&gt;Occupational histories were available for only 99 of the 198 discordant twin pairs and some of the information was obtained by proxy rather than from the participant himself.&lt;/p&gt;
&lt;p&gt;Because of the wide confidence intervals even for the yes-no exposure analysis, the findings need confirmation in a larger study, he said, noting that the best approach would be a cohort study involving people with known, long-term exposure to TCE, compared with well-chosen controls.&lt;/p&gt;
&lt;p&gt;&quot;The study wouldn&apos;t have to be large,&quot; Goldman said. He estimated that 1,000 to 2,000 participants would be adequate to determine if the connection to Parkinson&apos;s disease is real.&lt;/p&gt;
&lt;div style=&quot;float:left;border-style:solid;border-width:1px;border-color:#8dabbc;font-family:arial;font-size:12px;background-color:#DBE9F2;padding:5px;&quot;&gt;&lt;p&gt;The study was funded by the National Institute of Neurological Disorders and Stroke, the Valley Foundation, and the James and Sharron Clark Family Fund.&lt;/p&gt;&lt;p&gt;No potential conflicts of interest were reported.&lt;/p&gt;&lt;/div&gt;&lt;div style=&quot;clear:both;&quot;&gt;&lt;/div&gt;
    </recommendedItem>
    <recommendedItem id="20100101_19_372"
                     title="Low Serotonin Eyed as Mechanism for SIDS (CME/CE)"
                     score="0.009"
                     href="http://www.medpagetoday.com/Neurology/GeneralNeurology/tb/18262?impressionId=1265800831207"
                     
      Low brainstem levels of serotonin and the enzyme that makes it could underlie sudden infant death syndrome (SIDS), researchers suggested.&lt;br&gt;
&lt;br&gt;In an autopsy study, SIDS cases showed 26% lower serotonin levels in two major components of the medulla&apos;s serotonin system  --  the raph&amp;#233; obscurus (&lt;em&gt;P&lt;/em&gt;=0.05) and paragigantocellularis lateralis (&lt;em&gt;P&lt;/em&gt;=0.04)  --  compared with age-adjusted controls who died from known causes.&lt;br&gt;
&lt;br&gt;These brainstem circuits control breathing, blood pressure, and heart rate during sleep, Hannah C. Kinney, MD, of Children&apos;s Hospital Boston, and colleagues reported in the Feb. 3 issue of the &lt;em&gt;Journal of the American Medical Association&lt;/em&gt;.&lt;br&gt;
&lt;br&gt;A baby with an abnormality in control of these systems might not be able to respond to a life-threatening challenge like asphyxia by rousing from sleep or turning its head the researchers explained.&lt;p&gt;&lt;/p&gt;
&lt;p&gt;SIDS occurs in the &quot;critical first year of life, when homeostatic systems are still maturing,&quot; they noted.&lt;/p&gt;
&lt;p&gt;Mary McClain, RN, MS, of Boston University Medical Center, who counsels families that have lost a baby to SIDS, commented that these findings help establish the biological basis for urging parents to place their babies on their backs to sleep.&lt;/p&gt;
&lt;p&gt;The researchers obtained tissue samples from autopsies of 41 children who died from SIDS, seven who died acutely from known causes (including a car accident, drowning, pneumonia, and unsuspected congenital heart disease), and five who died in the hospital with chronic conditions causing hypoxia-ischemia.&lt;/p&gt;
&lt;p&gt;SIDS cases had mean serotonin levels of 31.4 pmol/mg of protein in the paragigantocellularis lateralis, compared with 40.0 pmol/mg among the controls who died acutely (&lt;em&gt;P&lt;/em&gt;=0.04).&lt;/p&gt;
&lt;p&gt;Levels averaged 55.4 versus 75.5 pmol/mg of protein, respectively, in the raph&amp;#233; obscurus (&lt;em&gt;P&lt;/em&gt;=0.05).&lt;/p&gt;
&lt;p&gt;These abnormalities in the medulla did not appear to involve the catecholamine system. Catecholamine levels were similar between SIDS cases and controls.&lt;/p&gt;
&lt;p&gt;Nor was there evidence for excessive degradation of dopamine or neurotransmitter turnover in SIDS cases, supporting the idea that the key abnormality is reduced synthesis of serotonin, the researchers said.&lt;/p&gt;
&lt;p&gt;Another marker of serotonin function  --  tryptophan hydroxylase (TPH2), the key enzyme involved in synthesis of serotonin  --  also supported this conclusion, with 22% lower levels in the raph&amp;#233; obscurus in SIDS than in controls (&lt;em&gt;P&lt;/em&gt;=0.03).&lt;/p&gt;
&lt;p&gt;Serotonin receptor binding was 29% to 55% lower in three medullary nuclei that receive serotonin projections, notable for a decrease in binding with older age in SIDS cases, but not controls, the researchers noted.&lt;/p&gt;
&lt;p&gt;Given similar findings in three previous investigations, this &quot;may reflect a progressive decrease with age in those infants with the &apos;SIDS abnormality,&apos;&quot; they wrote. Or it&apos;s possible that those with a &quot;stronger abnormality take longer to outgrow the risk period for SIDS and continue to die at older ages,&quot; Kinney&apos;s group wrote.&lt;/p&gt;
&lt;p&gt;Likewise, serotonin receptor binding in infants who died from SIDS was significantly lower in those without known risk factors for SIDS, such as &lt;a href=&quot;http://www.medpagetoday.com/Pediatrics/GeneralPediatrics/17365&quot; mce_href=&quot;http://www.medpagetoday.com/Pediatrics/GeneralPediatrics/17365&quot; target=&quot;_blank&quot;&gt;sleeping face down&lt;/a&gt;, &quot;suggesting that additional risk factors are necessary to precipitate death when the medullary serotonin system is less compromised,&quot; they added.&lt;/p&gt;
&lt;p&gt;Although repetitive apnea and agonal &lt;a href=&quot;http://www.medpagetoday.com/Pulmonology/SleepDisorders/2817&quot; mce_href=&quot;http://www.medpagetoday.com/Pulmonology/SleepDisorders/2817&quot; target=&quot;_blank&quot;&gt;impaired gasping&lt;/a&gt; before death have been reported in some SIDS cases, chronic impaired oxygenation in the hospitalized children in the study produced a very different serotonin pattern than that seen in SIDS.&lt;/p&gt;
&lt;p&gt;Children who died with chronic hypoxia conditions had 55% higher serotonin levels in the raph&amp;#233; obscurus (&lt;em&gt;P&lt;/em&gt;=0.02) and 126% higher levels in the paragigantocellularis lateralis (&lt;em&gt;P&lt;/em&gt;=0.002) than the SIDS cases.&lt;/p&gt;
&lt;p&gt;They also had 640% higher dopamine levels in the raph&amp;#233; obscurus than the SIDS cases (&lt;em&gt;P&lt;/em&gt;=0.006).&lt;/p&gt;
&lt;p&gt;This suggested &quot;that the primary mechanisms underlying serotonin abnormalities in SIDS are not mediated by chronic hypoxia-ischemia,&quot; Kinney&apos;s group wrote.&lt;/p&gt;
&lt;p&gt;The researchers cautioned that their neurotransmitter measurements may have been off somewhat due to prolonged postmortem intervals.&lt;/p&gt;
&lt;p&gt;They also warned that the study was limited by inability to perform these measurements at the synapse in postmortem tissues and by the small sample of controls.&lt;/p&gt;
&lt;div style=&quot;float:left;border-style:solid;border-width:1px;border-color:#8dabbc;font-family:arial;font-size:12px;background-color:#DBE9F2;padding:5px;&quot;&gt;&lt;p&gt;The study was supported by the First Candle/SIDS Alliance, CJ Martin Overseas Fellowship (National Health and Medical Research Council of Australia), CJ Murphy Foundation for Solving the Puzzle of SIDS, CJ Foundation for SIDS, National Institute of Child Health and Development, and the Developmental Disabilities Research Center at Children&apos;s Hospital Boston.&lt;/p&gt;&lt;p&gt;The researchers reported no conflicts of interest.&lt;/p&gt;&lt;p&gt;McClain provided no information on conflicts of interest.&lt;/p&gt;&lt;/div&gt;&lt;div style=&quot;clear:both;&quot;&gt;&lt;/div&gt;
    </recommendedItem>
    <recommendedItem id="20090101_4_489"
                     title="AAN: In Utero Exposure to Valproate Lowers IQ"
                     score="-0.005"
                     href="