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Hunter MD, Moon YP, Miller EC, Kulick ER, Boehme AK, Elkind MS. Influenza-Like Illness is Associated with Increased Short-Term Risk of Cervical Artery Dissection. J Stroke Cerebrovasc Dis 2021; 30:105490. [PMID: 33253984 PMCID: PMC10086675 DOI: 10.1016/j.jstrokecerebrovasdis.2020.105490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 10/22/2022] Open
Abstract
INTRODUCTION Non-traumatic Cervical Artery Dissection (CeAD) is a leading cause of ischemic stroke in the young. Influenza-like illnesses (ILI) trigger ischemic strokes. We hypothesized that influenza and ILI are associated with CeAD. METHODS In a case-crossover study within the New York State (NYS) Department of Health Statewide Planning and Research Cooperative System (2006-2014), we used ICD-9 codes to exclude major trauma and to define CeAD, influenza, and the Centers for Disease Control defined ILI. We estimated the association of ILI and influenza with CeAD by comparing their prevalence in intervals immediately prior (0-30,0-90,0-180, and 0-365 days) to CeAD (case period) to their prevalence exactly one and two years earlier (control periods). Conditional logistic regression models generated odds ratios and 95% confidence intervals (OR, 95% CI). Models were adjusted for NYS estimates of influenza prevalence rates. RESULTS Our sample included 3,610 cases of CeAD (mean age 52±16 years, 54.7% male, 6.2% Hispanic, 9.9% Black, 68.7% White). During case periods, 7.3% had one or more ILI. ILI was more likely within 90 days of CeAD compared to the same time interval one and two years before (0-15 days: adjusted OR 1.88, 95%CI 1.20-2.94; 0-30 days: adjusted OR 1.74, 95%CI 1.22-2.46; 0-90 days: adjusted OR 1.35, 95%CI 1.00-1.81). Influenza trended with CeAD (adjusted OR 1.86, 95%CI 0.37-9.24), but these results were not statistically significant, due to limited instances of confirmed influenza. CONCLUSIONS ILI may increase risk of CeAD for 15 days, and possibly up to three months.
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Affiliation(s)
- Madeleine D Hunter
- Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA.
| | - Yeseon P Moon
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA.
| | - Eliza C Miller
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA.
| | - Erin R Kulick
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA.
| | - Amelia K Boehme
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York City, NY, USA.
| | - Mitchell Sv Elkind
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA; Department of Epidemiology and Biostatistics, Temple University College of Public Health, Philadelphia, PA, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York City, NY, USA.
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Kummer BR, Lerario MP, Hunter MD, Wu X, Efraim ES, Salehi Omran S, Chen ML, Diaz IL, Sacchetti D, Lekic T, Kulick ER, Pishanidar S, Mir SA, Zhang Y, Asaeda G, Navi BB, Marshall RS, Fink ME. Geographic Analysis of Mobile Stroke Unit Treatment in a Dense Urban Area: The New York City METRONOME Registry. J Am Heart Assoc 2019; 8:e013529. [PMID: 31795824 PMCID: PMC6951069 DOI: 10.1161/jaha.119.013529] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Background Mobile stroke units (MSUs) reduce time to intravenous thrombolysis in acute ischemic stroke. Whether this advantage exists in densely populated urban areas with many proximate hospitals is unclear. Methods and Results We evaluated patients from the METRONOME (Metropolitan New York Mobile Stroke) registry with suspected acute ischemic stroke who were transported by a bi-institutional MSU operating in Manhattan, New York, from October 2016 to September 2017. The comparison group included patients transported to our hospitals via conventional ambulance for acute ischemic stroke during the same hours of MSU operation (Monday to Friday, 9 am to 5 pm). Our exposure was MSU care, and our primary outcome was dispatch-to-thrombolysis time. We estimated mean differences in the primary outcome between both groups, adjusting for clinical, demographic, and geographic factors, including numbers of nearby designated stroke centers and population density. We identified 66 patients treated or transported by MSU and 19 patients transported by conventional ambulance. Patients receiving MSU care had significantly shorter dispatch-to-thrombolysis time than patients receiving conventional care (mean: 61.2 versus 91.6 minutes; P=0.001). Compared with patients receiving conventional care, patients receiving MSU care were significantly more likely to be picked up closer to a higher mean number of designated stroke centers in a 2.0-mile radius (4.8 versus 2.7, P=0.002). In multivariable analysis, MSU care was associated with a mean decrease in dispatch-to-thrombolysis time of 29.7 minutes (95% CI, 6.9-52.5) compared with conventional care. Conclusions In a densely populated urban area with a high number of intermediary stroke centers, MSU care was associated with substantially quicker time to thrombolysis compared with conventional ambulance care.
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Affiliation(s)
- Benjamin R Kummer
- Department of Neurology Icahn School of Medicine at Mount Sinai New York NY
| | - Mackenzie P Lerario
- Department of Neurology NewYork-Presbyterian Queens Flushing NY.,Department of Neurology Weill Cornell Medicine New York NY.,Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | | | - Xian Wu
- Department of Healthcare Policy and Research Weill Cornell Medicine New York NY
| | | | - Setareh Salehi Omran
- Department of Neurology Weill Cornell Medicine New York NY.,Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | - Monica L Chen
- Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | - Ivan L Diaz
- Department of Healthcare Policy and Research Weill Cornell Medicine New York NY
| | - Daniel Sacchetti
- Department of Neurology Brown Alpert School of Medicine Providence RI
| | - Tim Lekic
- Desert Neurology & Sleep La Quinta CA
| | - Erin R Kulick
- School of Public Health Brown University Providence RI
| | - Sammy Pishanidar
- Department of Neurology NewYork-Presbyterian Queens Flushing NY.,Department of Neurology Weill Cornell Medicine New York NY.,Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | - Saad A Mir
- Department of Neurology Weill Cornell Medicine New York NY.,Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | - Yi Zhang
- New York University Winthrop Hospital Mineola NY
| | | | - Babak B Navi
- Department of Neurology Weill Cornell Medicine New York NY.,Clinical Translational Neuroscience Unit Feil Family Brain & Mind Research Institute Weill Cornell Medicine New York NY
| | - Randolph S Marshall
- Department of Neurology Columbia College of Physicians & Surgeons New York NY
| | - Matthew E Fink
- Department of Neurology Weill Cornell Medicine New York NY
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Kummer BR, Lerario MP, Hunter MD, Efraim ES, Wu X, Omran SS, Diáz I, Lekic T, Sacchetti D, Kulick ER, Pishanidar S, Mir SA, Zhang Y, Asaeda G, Navi BB, Marshall RS, Fink ME. Abstract 167: Geographic Analysis of Mobile Stroke Unit Treatment in a Densely Populated Urban Area: The New York City METRONOME Registry. Stroke 2019. [DOI: 10.1161/str.50.suppl_1.167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Benjamin R Kummer
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | - Michael P Lerario
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | | | | | - Xian Wu
- Healthcare Policy and Rsch, Weill Cornell Medicine, New York, NY
| | - Setareh S Omran
- Neurology, Columbia Univ College of Physicians & Surgeons, New York, NY
| | - Iván Diáz
- Healthcare Policy and Rsch, Weill Cornell Medicine, New York, NY
| | - Tim Lekic
- Desert Neurology & Sleep, La Quinta, CA
| | - Daniel Sacchetti
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | - Erin R Kulick
- Neurology, Columbia Univ College of Physicians & Surgeons, New York, NY
| | - Sammy Pishanidar
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | - Saad A Mir
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | - Yi Zhang
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
| | | | - Babak B Navi
- Clinical and Translational Neuroscience Unit, Feil Family Brain and Mind Rsch Institute and Dept of Neurology, New York, NY
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Hunter MD, Moon YP, Kulick ER, Boehme AK, Elkind MS. Abstract WMP49: Influenza-Like Illness May Trigger Cervical Artery Dissection. Stroke 2019. [DOI: 10.1161/str.50.suppl_1.wmp49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose:
Non-traumatic Cervical Artery Dissection (CeAD) is a leading cause of ischemic stroke in patients 15 to 45 years old. Influenza-like illnesses (ILI) have been found to trigger ischemic stroke, but ILI has not been investigated in relation to CeAD. We hypothesized that ILI and influenza would be associated with CeAD.
Methods:
We used a case-crossover design among patients
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18 years old at time of first non-traumatic CeAD within the New York State (NYS) Department of Health Statewide Planning and Research Cooperative System (2006-2014). We used ICD-9 codes to define CeAD (443.21, 443.24) excluding individuals with major trauma (integer values 800-804 and 850-854), confirmed influenza (480, 487.0, 487.1, 487.8), and a broader influenza definition endorsed by the CDC for ILI surveillance. We compared ILI and influenza in sequential, mutually exclusive intervals preceding CeAD (0-15, 16-30, 31-90, 91-180, and 181-365 days prior to CeAD: case period) and overlapping intervals (0-30, 0-90, 0-180, and 0-365 days prior to CeAD: alternate case period) to ILI and influenza exactly one and two years earlier (control periods). Conditional logistic regression models were used to calculate odds ratios and 95% confidence intervals (OR, 95% CI) before and after adjusting for annual NYS population estimates of influenza prevalence rate.
Results:
Our final sample included 3,861 cases of CeAD (mean age 52±16 and 55.5% of male). We found 1,736 instances of ILI and 113 of influenza during the 3 years preceding CeAD. Patients were more likely to have ILI within 30 days of CeAD compared to the same time one and two years before (0-15 days: adjusted OR 1.53, 95% CI 1.02 - 2.30; 0-30 days: adjusted OR 1.60, 95% CI 1.14 - 2.23). ILI during later overlapping or sequential intervals was not associated with CeAD in adjusted models. Influenza was associated with CeAD between 31 and 90 days after CeAD, but this effect was no longer significant after adjusting for prevalence rate of influenza, perhaps due the small number of patients with confirmed influenza.
Conclusions:
ILI may increase risk of CeAD for up to one month. Further research on mechanisms by which ILI and influenza may trigger dissection are warranted.
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Affiliation(s)
| | - Yeseon P Moon
- Neurology, Vagelos College of Physicians and Surgeons, Columbia Univ, New York, NY
| | | | - Amelia K Boehme
- Neurology and Epidemiology, Vagelos College of Physicians and Surgeons, Columbia Univ, New York, NY
| | - Mitchell S Elkind
- Neurology and Epidemiology, Vagelos College of Physicians and Surgeons, Columbia Univ, New York, NY
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Valenzuela I, Hunter MD, Sundheim K, Klein B, Dunn L, Sorabella R, Han SM, Willey J, George I, Gutierrez J. Clinical risk factors for acute ischaemic and haemorrhagic stroke in patients with infective endocarditis. Intern Med J 2019; 48:1072-1080. [PMID: 29740951 DOI: 10.1111/imj.13958] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/20/2018] [Accepted: 04/21/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Stroke as a complication of infective endocarditis portends a poor prognosis, yet risk factors for stroke subtypes have not been well defined. AIM To identify risk factors associated with ischaemic and haemorrhagic strokes. METHODS A retrospective patient chart review was performed at a single US academic centre to identify risk factors and imaging for patients who were 18 years or older with infectious endocarditis (IE) and stroke diagnoses. Differences in patient characteristics by stroke status were assessed using univariate analysis, χ2 or student's t-test as well as logistic regression models for multivariable analyses and correlation matrices to identify possible collinearity between variables and to obtain odds ratios (OR) and their 95% confidence intervals. RESULTS A final sample of 1157 participants was used for this analysis. The total number of non-surgical strokes was 178, with a prevalence of 15.4% (78% ischaemic, 10% parenchymal haemorrhages, 8% subarachnoid haemorrhages and 4% mixed ischaemic/haemorrhagic). Multivariate risk factors for ischaemic stroke included prior stroke (OR 2.0, 1.3-3.1), Staphylococcus infection (OR 2.0, 1.3-3.0), mitral vegetations (OR 2.2, 1.4-3.3) and valvular abscess (OR 2.7, 1.7-4.3). Risk factors for haemorrhagic stroke included fungal infection (OR 6.4, 1.2-34.0), male gender (OR 3.5, 1.4-8.3) and rheumatic heart disease (OR 3.3, 1.1-10.4). CONCLUSION Among patients with IE, there exist characteristics that relate differentially to ischaemic and haemorrhagic stroke risk.
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Affiliation(s)
- Ives Valenzuela
- College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Madeleine D Hunter
- College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Kathryn Sundheim
- College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Bradley Klein
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
| | - Lauren Dunn
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
| | - Robert Sorabella
- Division of Cardiothoracic Surgery, Columbia University Medical Center, New York, New York, USA
| | - Sang M Han
- Division of Cardiothoracic Surgery, Columbia University Medical Center, New York, New York, USA
| | - Joshua Willey
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
| | - Isaac George
- Division of Cardiothoracic Surgery, Columbia University Medical Center, New York, New York, USA
| | - Jose Gutierrez
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
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Hunter MD, Moon YP, Varela D, DeCarli C, Gutierrez J, Wright CB, Di Tullio MR, Sacco RL, Kamel H, Elkind MS. Abstract WP176: Electrocardiographic Left Atrial Abnormality and Silent Vascular Brain Injury: The Northern Manhattan Study. Stroke 2016. [DOI: 10.1161/str.47.suppl_1.wp176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Increased P-wave terminal force in lead V1 (PTFV1) of a standard 12-lead electrocardiogram (EKG), a marker of left atrial dilatation and possibly fibrosis, has been associated with stroke risk in the absence of atrial fibrillation (AF), and with subclinical infarcts in some cohorts. We hypothesized that PTFV1 would be associated with an increased prevalence of subclinical infarcts, especially cortical ones, and leukoaraiosis in a population-based, multi-ethnic cohort.
Methods:
PTFV1 was collected manually from baseline EKGs of participants in the population-based, prospective Northern Manhattan Study (NOMAS) who had remained clinically stroke-free and undergone brain MRI (n=1,290). MRIs were read for superficial and deep infarcts and white matter hyperintensity volume adjusted for head size (WMHV). Logistic regression models were used for the association of PTFV1 with all subclinical infarcts and with cortical infarcts, and linear regression models with logWMHV. Models were adjusted for demographics and risk factors.
Results:
Among the 1174 participants with PTFV1, mean age was 70 + 9 SD years at the time of MRI, 40.3% were male, and 14.4% were white, 17.6% black, and 65.8% Hispanic. Hypertension was present in 68.0%. Mean PTFV1 was 3587.35 ± 2315.62 μV-ms. MRIs were performed a mean of 6.0 + 3.4 years after EKG. Subclinical infarcts were present in 170 (15.1%) participants, and were cortical in 40 (3.6%). PTFV1 >5000 μV-ms was associated with greater WMHV even after adjusting for demographics and risk factors, including baseline AF (mean difference in logWMHV 0.14, 95% CL 0.01-0.28). There was a trend toward an association of PTFV1 with cortical (unadjusted OR per SD change logPTFV1 1.30, 95% CI 0.94-1.81) but not with all subclinical infarcts (unadjusted OR 1.00, 95% CI 0.85-1.18).
Conclusion:
EKG evidence of left atrial abnormality was associated with leukoaraiosis, and possibly with subclinical cortical infarcts, though the limited number of outcomes did not permit us to confirm this finding. Left atrial cardiopathy may be a source of emboli, but may also cause cerebral hypoperfusion-related injury. Further studies in large cohorts are needed to determine the relationship of PTFV1 to risk of subclinical cerebrovascular disease.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hooman Kamel
- Neurology, Weill Sch of Medicine, Cornell Univ, New York, NY
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Nazimek JM, Hunter MD, Hoskin R, Wilkinson I, Woodruff PW. Neural basis of auditory expectation within temporal cortex. Neuropsychologia 2013; 51:2245-50. [PMID: 23933483 DOI: 10.1016/j.neuropsychologia.2013.07.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 07/08/2013] [Accepted: 07/24/2013] [Indexed: 10/26/2022]
Abstract
Predictive coding frameworks of perception propose that neural networks form predictions of expected input and generate prediction errors when the external input does not match expectation. We therefore investigated the processing of unexpected sounds and silence in the auditory cortex using fMRI. Unexpected sounds, when compared to expected sounds, evoked greater activation in large areas of the left temporal and insular cortices. Additionally the left middle temporal gyrus exhibited greater activation to unexpected events in general, whether sounds or silence, when compared to the corresponding expected events. These findings support predictive coding models of perception, which suggest that regions of the temporal cortex function to integrate sensory information with predictive signals during auditory perception.
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Affiliation(s)
- J M Nazimek
- Sheffield Cognition and Neuroimaging Laboratory (SCANlab), Academic Clinical Psychiatry, Department of Neuroscience, Faculty of Medicine, Dentistry and Health, University of Sheffield, Yorkshire, UK.
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Abstract
The following article discusses the phenomenon of auditory hallucinations in those who do not suffer from schizophrenia. Research has shown the occurrence of auditory hallucinations in the general population to such an extent that they cannot be said to be pathognomonic of psychiatric illness. In addition, it has long been known that certain hallucinatory experiences occur in health, such as hypnagogic and hypnopompic hallucinations. However, there are fundamental differences in the characteristics of these experiences. In the psychiatric population, these tend to be frequent, intrusive, and distressing. In contrast, in the nonclinical population, these are often predominantly positive and nonthreatening. The exact mechanism for the occurrence of auditory hallucinations is not yet known, but it is hoped that through the study of those in health, the mechanisms that underpin pathophysiologic processes in clinical conditions also can be elucidated.
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Affiliation(s)
- C Choong
- Department of Academic Clinical Psychiatry, SCANLab (Sheffield Cognition and Neuroimaging Laboratory), The University of Sheffield, The Longley Centre, Sheffield S5 7JT, United Kingdom
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Kominoski JS, Pringle CM, Ball BA, Bradford MA, Coleman DC, Hall DB, Hunter MD. NONADDITIVE EFFECTS OF LEAF LITTER SPECIES DIVERSITY ON BREAKDOWN DYNAMICS IN A DETRITUS-BASED STREAM. Ecology 2007; 88:1167-76. [PMID: 17536403 DOI: 10.1890/06-0674] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Since species loss is predicted to be nonrandom, it is important to understand the manner in which those species that we anticipate losing interact with other species to affect ecosystem function. We tested whether litter species diversity, measured as richness and composition, affects breakdown dynamics in a detritus-based stream. Using full-factorial analyses of single- and mixed-species leaf packs (15 possible combinations of four dominant litter species; red maple [Acer rubrum], tulip poplar [Liriodendron tulipifera], chestnut oak [Quercus prinus], and rhododendron [Rhododendron maximum]), we tested for single-species presence/absence (additive) or species interaction (nonadditive) effects on leaf pack breakdown rates, changes in litter chemistry, and microbial and macroinvertebrate biomass. Overall, we found significant nonadditive effects of litter species diversity on leaf pack breakdown rates, which were explained both by richness and composition. Leaf packs containing higher litter species richness had faster breakdown rates, and antagonistic effects of litter species composition were observed when any two or three of the four litter species were mixed. Less-consistent results were obtained with respect to changes in litter chemistry and microbial and macroinvertebrate biomass. Our results suggest that loss of litter species diversity will decrease species interactions involved in regulating ecosystem function. To that end, loss of species such as eastern hemlock (Tsuga canadensis) accompanied by predicted changes in riparian tree species composition in the southeastern United States could have nonadditive effects on litter breakdown at the landscape scale.
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Affiliation(s)
- J S Kominoski
- Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA.
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Hunter MD, Eickhoff SB, Miller TWR, Farrow TFD, Wilkinson ID, Woodruff PWR. Neural activity in speech-sensitive auditory cortex during silence. Proc Natl Acad Sci U S A 2005; 103:189-94. [PMID: 16371474 PMCID: PMC1317878 DOI: 10.1073/pnas.0506268103] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
That auditory hallucinations are voices heard in the absence of external stimuli implies the existence of endogenous neural activity within the auditory cortex responsible for their perception. Further, auditory hallucinations occur across a range of healthy and disease states that include reduced arousal, hypnosis, drug intoxication, delirium, and psychosis. This suggests that, even in health, the auditory cortex has a propensity to spontaneously "activate" during silence. Here we report the findings of a functional MRI study, designed to examine baseline activity in speech-sensitive auditory regions. During silence, we show that functionally defined speech-sensitive auditory cortex is characterized by intermittent episodes of significantly increased activity in a large proportion (in some cases >30%) of its volume. Bilateral increases in activity are associated with foci of spontaneous activation in the left primary and association auditory cortices and anterior cingulate cortex. We suggest that, within auditory regions, endogenous activity is modulated by anterior cingulate cortex, resulting in spontaneous activation during silence. Hence, an aspect of the brain's "default mode" resembles a (preprepared) substrate for the development of auditory hallucinations. These observations may help explain why such hallucinations are ubiquitous.
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Affiliation(s)
- M D Hunter
- Sheffield Cognition and Neuroimaging Laboratory (SCANLab), Academic Clinical Psychiatry, Division of Genomic Medicine, University of Sheffield, Sheffield S5 7JT, United Kingdom.
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12
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Hunter MD, Mysorekar S, Woodruff PWR. Visual broadcast in schizophrenia. Med Humanit 2005; 31:55. [PMID: 23674652 DOI: 10.1136/jme.2005.000211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- M D Hunter
- The University of Sheffield, School of Medicine & Biomedical Sciences, Academic Clinical Psychiatry, The Longley Centre, NGH, Norwood Grange Drive, Sheffield S5 7JT
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Kearns KD, Hunter MD. Algal extracellular products suppress Anabaena flos-aquae heterocyst spacing. Microb Ecol 2002; 43:174-180. [PMID: 11984639 DOI: 10.1007/s00248-001-1039-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2001] [Accepted: 09/06/2001] [Indexed: 05/23/2023]
Abstract
Intra- and interspecific chemical signals allow bacteria to respond to environmental conditions by regulating gene transcription. In cyanobacteria, gene products and the presence of fixed nitrogen regulate heterocyst frequency. In this paper, we describe a chemical made by a green alga, Chlamydomonas reinhardtii, that suppresses heterocyst formation in the co-occurring cyanobacterium, Anabaena flos-aquae. Cyanobacterial heterocyst frequencies were reduced in the presence of water-soluble, proteinase- and heat-resistant molecules greater than 15 kDa in molecular size. Green algal cells in all phases of growth made the suppressor. Ammonium and nitrate concentrations in the medium did not correlate with this change in phenotype. In addition, growth rate was not enhanced by the extracellular products. Therefore, C. reinhardtii extracellular products acted as a heterocyst inhibitor, not as a fixed nitrogen source. Chemical interactions between green algae and cyanobacteria influence heterocyst formation, an important consideration in understanding the outcome of competition between these organisms and the dynamics of phytoplankton communities.
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Affiliation(s)
- K D Kearns
- Institute of Ecology, University of Georgia, Athens, GA 30602-2202, USA.
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Abstract
In a common garden, we investigated genetic and environmental influences on alkaloid production using Sanguinaria canadensis as a model. Nutrient and shade regimes were applied to replicated clones over one growing season, and induction of alkaloid production in bloodroot was tested on a whole-plant basis using jasmonic acid as an elicitor. Alkaloid concentrations increased with decreasing light intensity and fertilizer levels. Induction was not achieved by foliar application of jasmonic acid. Genetic influences represented by clone effects may be indicated by variation in alkaloid concentration by clone, but this experimental design did not allow us to distinguish genetic from pre-experiment environmental influences on the rhizomes.
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Affiliation(s)
- A K Salmore
- Institute of Ecology, University of Georgia, Athens 30602, USA
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Abstract
Studies of quantitative inheritance of phenotypes do not generally encompass the range of environmental conditions to which a population may be exposed in a natural setting and are rarely conducted on long-lived species due to the time required for traditional crossing experiments. We used a marker-based method to estimate relatedness with microsatellite markers in a natural population of a long-lived oak, then used this inferred relatedness to examine quantitative genetic variation in the concentration of foliar phenolics. Estimating heritability using this method requires both significant relatedness and variance in relatedness over distance. However, this population did not show significant variance of relatedness, so only the presence of heritability, and its ranking among traits and environments, could be estimated. Seven foliar phenolics showed a significant relationship between phenotypic similarity and relatedness. The significance of this relationship varied among individual phenolic compounds, as well as by season. Genetic factors appeared to have a more measurable influence on the production of secondary compounds early in the season. After leaf expansion, covariance of relatedness and phenotypic variance appear to become less significant. Therefore heritability may vary seasonally for these traits.
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Affiliation(s)
- R Klaper
- Department of Entomology, 4112 Plant Sciences, University of Maryland, College Park, MD 20742, USA.
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16
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Abstract
Evaluation of biotic interactions along geographic gradients reveals that pressure on plant populations by herbivores and pathogens increases as latitude decreases, and is accompanied by a parallel increase in the number and toxicity of alkaloid-bearing plants. We compared rhizome alkaloid content with plant reproductive and vegetative characters in Sanguinaria canadensis (Papaveraceae) along an elevational gradient over two growing seasons to ascertain 1) if alkaloid production in bloodroot varies among populations and systematically with elevation, and 2) if there exists a correlation between isoquinoline alkaloid, vegetative and reproductive production. In general, alkaloid content in bloodroot rhizomes declines with elevation, increases with rhizome water content, varies by site, and fluctuates seasonally with plant growth and reproduction. Alkaloid content was positively correlated with vegetative and reproductive effort with few exceptions. Analysis of total protopine and benzophenanthridine alkaloid concentrations revealed generally similar patterns as those of individual alkaloid concentrations, although significant differences did appear between individual alkaloid concentrations.
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Affiliation(s)
- A K Salmore
- Institute of Ecology, University of Georgia, Athens 30602, USA
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17
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Abstract
Many populations of the buprestid leaf-mining beetle, Brachys tessellatus, from central South Carolina, USA, show highly skewed sex ratios, ranging from 1.3 to 6.0 females per male. We have identified a Rickettsia bacterium that is associated with sex ratio distortion (SRD) and selective killing of male embryos in B. tessellatus. Molecular assays of infection by this bacterium are highly associated with SRD within families, and treatment with an antibiotic (tetracycline) increases the number of male eggs that hatch and develop. The 16S rDNA sequence indicates that this is a novel Rickettsia, most closely related to Rickettsia bellii (a tick-associated bacterium) and a pea-aphid Rickettsia. It is also related to a Rickettsial bacterium that causes male-killing in an unrelated ladybird beetle species. Low levels of parthenogenesis are also observed in this system (about 10% of females) and may be the result of selection due to male rarity, or a direct result of infection by the Rickettsia.
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Affiliation(s)
- E T Lawson
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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18
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Sebulsky MT, Hohnstein D, Hunter MD, Heinrichs DE. Identification and characterization of a membrane permease involved in iron-hydroxamate transport in Staphylococcus aureus. J Bacteriol 2000; 182:4394-400. [PMID: 10913070 PMCID: PMC94608 DOI: 10.1128/jb.182.16.4394-4400.2000] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus was shown to transport iron complexed to a variety of hydroxamate type siderophores, including ferrichrome, aerobactin, and desferrioxamine. An S. aureus mutant defective in the ability to transport ferric hydroxamate complexes was isolated from a Tn917-LTV1 transposon insertion library after selection on iron-limited media containing aerobactin and streptonigrin. Chromosomal DNA flanking the Tn917-LTV1 insertion was identified by sequencing of chromosomal DNA isolated from the mutant. This information localized the transposon insertion to a gene whose predicted product shares significant similarity with FhuG of Bacillus subtilis. DNA sequence information was then used to clone a larger fragment of DNA surrounding the fhuG gene, and this resulted in the identification of an operon of three genes, fhuCBG, all of which show significant similarities to ferric hydroxamate uptake (fhu) genes in B. subtilis. FhuB and FhuG are highly hydrophobic, suggesting that they are embedded within the cytoplasmic membrane, while FhuC shares significant homology with ATP-binding proteins. Given this, the S. aureus FhuCBG proteins were predicted to be part of a binding protein-dependent transport system for ferric hydroxamates. Exogenous iron levels were shown to regulate ferric hydroxamate uptake in S. aureus. This regulation is attributable to Fur in S. aureus because a strain containing an insertionally inactivated fur gene showed maximal levels of ferric hydroxamate uptake even when the cells were grown under iron-replete conditions. By using the Fur titration assay, it was shown that the Fur box sequences upstream of fhuCBG are recognized by the Escherichia coli Fur protein.
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Affiliation(s)
- M T Sebulsky
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada, N6A 5C1
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19
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Abstract
Many bacterial genes and virulence factors are regulated by interbacterial and/or host-parasite chemical signals. We demonstrate that toxin production by a free-living freshwater cyanobacterium is regulated in part by the presence of extracellular products of a eukaryotic green alga. In growth experiments, extracellular products made by the cyanobacterium Anabaena flos-aquae contained both anatoxin and microcystin, and significantly reduced the yield of Chlamydomonas reinhardtii, a green alga. Based on experiments in which we added purified toxins to C. reinhardtii cultures, we believe that microcystin was responsible for the growth reduction. A. flos-aquae produced anatoxin constitutively when grown alone, but anatoxin concentration increased in the presence of C. reinhardtii elicitors. Microcystin accumulation depended on the growth phase; however, high concentrations of C. reinhardtii extracellular products completely inhibited microcystin accumulation. Our results demonstrate that cyanobacterial toxin production may be regulated by complex growth phase-dependent and environmental chemical cues, and suggest that secreted chemicals can mediate the outcome of competition between the cyanobacterium A. flos-aquae and the green alga C. reinhardtii.
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Affiliation(s)
- K D Kearns
- Institute of Ecology, University of Georgia, Athens 30602-2202, USA.
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20
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Hunter MD, Varley GC, Gradwell GR. Estimating the relative roles of top-down and bottom-up forces on insect herbivore populations: a classic study revisited. Proc Natl Acad Sci U S A 1997; 94:9176-81. [PMID: 11038566 PMCID: PMC23094 DOI: 10.1073/pnas.94.17.9176] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although most ecologists agree that both top-down and bottom-up forces (predation and resource limitation, respectively) act in concert to influence populations of herbivores, it has proven difficult to estimate the relative contributions of such forces in terrestrial systems. Using a combination of time-series analysis of population counts recorded over 16 years and experimental data, we present the first estimates of the relative roles of top-down and bottom-up forces on the population dynamics of two terrestrial insect herbivores on the English oak (Quercus robur). Data suggest that temporal variation in winter moth, Operophtera brumata, density is dominated by time-lagged effects of pupal predators. By comparison, spatial variation in O. brumata density is dominated by host-plant quality. Overall, top-down forces explain 34.2% of population variance, bottom-up forces explain 17.2% of population variance, and 48.6% remains unexplained. In contrast, populations of the green oak tortrix, Tortrix viridana, appear dominated by bottom-up forces. Resource limitation, expressed as intraspecific competition among larvae for oak leaves, explains 29.4% of population variance. Host quality effects explain an additional 5.7% of population variance. We detected no major top-down effects on T. viridana populations. An unknown factor causing a linear decline in T. viridana populations over the 16-year study period accounts for most of the remaining unexplained variance. We discuss the observed differences between the insect species and the utility of time-series analysis as a tool in assessing the relative importance of top-down and bottom-up forces on herbivore populations.
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Affiliation(s)
- M D Hunter
- Institute of Ecology, University of Georgia, Athens, GA 30602-2202, USA
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21
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Hunter MD, Robinson IC, Neilson S. The functional and psychological status of patients with amyotrophic lateral sclerosis: some implications for rehabilitation. Disabil Rehabil 1993; 15:119-26. [PMID: 8374156 DOI: 10.3109/09638289309166002] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Amyotrophic lateral sclerosis (ALS), known as motor neurone disease (MND) in Britain, poses special problems in rehabilitation by virtue of its nature, trajectory and the age of patients with the disease. Many practical difficulties of ALS are well known, but there has been little research on the psychological parameters of the disease. This study of 181 ALS patients, from a national register in England and Wales, indicates that, contrary to some previous research, psychological distress (measured by the General Health Questionnaire) is widespread among patients at all stages of the disease. Severity of functional impairment is significantly related to psychological distress, but explains only a small part of the variance. Rehabilitation in relation to ALS must take account of the high incidence of psychological difficulties, as well as the considerable functional problems associated with the disease.
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Affiliation(s)
- M D Hunter
- MND Research Unit, Brunel University of West London, Uxbridge, Middlesex, UK
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