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Search Results: 1 - 10 of 195062 matches for " Ronald D. Chervin "
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Fatigue, Tiredness, Lack of Energy, and Sleepiness in Multiple Sclerosis Patients Referred for Clinical Polysomnography
Tiffany J. Braley,Ronald D. Chervin,Benjamin M. Segal
Multiple Sclerosis International , 2012, DOI: 10.1155/2012/673936
Fatigue, Tiredness, Lack of Energy, and Sleepiness in Multiple Sclerosis Patients Referred for Clinical Polysomnography
Tiffany J. Braley,Ronald D. Chervin,Benjamin M. Segal
Multiple Sclerosis International , 2012, DOI: 10.1155/2012/673936
Abstract: Objectives. To assess the relationship between nocturnal polysomnographic (PSG) findings and a group of key self-reported symptoms—fatigue, tiredness, lack of energy, and sleepiness—among sleep-laboratory referred patients with and without multiple sclerosis (MS). Methods. PSG and questionnaire data from MS patients and matched controls were analyzed retrospectively. Associations between symptoms of fatigue, tiredness, lack of energy, sleepiness, and PSG variables of interest were examined among MS patients and controls. Results. More MS patients than controls reported fatigue, tiredness, and lack of energy to occur often or almost always (Chi-square for each), but sleepiness was reported similarly by both groups ( ). Among MS patients, tiredness correlated with sleepiness (Spearman correlation ), and a trend emerged toward correlation between fatigue and sleepiness (Spearman correlation ). Decreased sleep efficiency on PSGs correlated with fatigue, tiredness, and lack of energy in MS patients (Spearman correlation , 0.029, and 0.048, resp.), but not sleepiness or any symptom among controls. Conclusion. In comparison to controls, MS patients report more fatigue, tiredness, and lack energy, but not sleepiness. Fatigue and related symptoms may arise from MS itself or in relation to reduced sleep efficiency. 1. Introduction Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that causes myelin destruction and axonal damage in the brain and spinal cord. It is the leading cause of nontraumatic neurological disability among young adults and is associated with a variety of debilitating symptoms, including fatigue. Fatigue is the most common symptom experienced by persons with MS, affecting up to 90% of patients at some point in their disease course [1–3]. Fatigue imposes significant socioeconomic consequences, including loss of work hours and employment [4], and is a prominent cause of diminished quality of life among individuals with MS [3]. Despite its prevalence in MS as well as other medical conditions, there is no unified definition for fatigue. Consequently, there is potential for considerable overlap between fatigue and other subjective terms commonly used by MS patients to describe lack of energy or alertness, including sleepiness. Sleep disorders are traditionally recognized for their contributions to excessive daytime sleepiness. However, many subjects in the general population who have sleep disorders such as obstructive sleep apnea report that problems with fatigue, tiredness, or lack of energy supersede problems with
Asthma Control and Its Relationship with Obstructive Sleep Apnea (OSA) in Older Adults
Mihaela Teodorescu,David A. Polomis,Ronald E. Gangnon,Jessica E. Fedie,Flavia B. Consens,Ronald D. Chervin,Mihai C. Teodorescu
Sleep Disorders , 2013, DOI: 10.1155/2013/251567
Abstract: Background/Objectives. Asthma in older individuals is poorly understood. We aimed to characterize the older asthma phenotype and test its association with obstructive sleep apnea (OSA). Design. Cross-sectional. Setting. Pulmonary and Asthma/Allergy clinics. Participants. 659 asthma subjects aged 18–59 years (younger) and 154 aged 60–75 (older). Measurements. Sleep Apnea scale of Sleep Disorders Questionnaire (SA-SDQ), asthma severity step (1–4, severe if step 3 or 4), established OSA diagnosis, continuous positive airway pressure (CPAP) use, and comorbidities. Results. Older versus younger had worse control, as assessed by asthma step, lung function, and inhaled corticosteroid use. Among older subjects, after controlling for known asthma aggravators, OSA diagnosis was the only factor robustly associated with severe asthma: on average, OSA was associated with nearly 7 times greater likelihood of severe asthma in an older individual ( ). This relationship was of greater magnitude than in younger subjects ( ). CPAP use attenuated the likelihood of severe asthma in older subjects by 91% ( ), much more than in the younger asthmatics. Conclusion. Diagnosed OSA increases the risk for worse asthma control in older patients, while CPAP therapy may have greater impact on asthma outcomes. Unrecognized OSA may be a reason for poor asthma control, particularly among older patients. 1. Introduction Asthma is a major health problem in the general population. As many patients develop asthma in childhood or adolescence, large community studies have focused on asthma in early years. While the prevalence is estimated to be 6.5–17% [1] and may be similar to that seen in younger adults, asthma is frequently underrecognized as a geriatric respiratory disorder and often remains undiagnosed [2]. This may be due to the fact that older adults tend to underreport symptoms, have limited subjective awareness, lack perception or attribution to pulmonary pathology [2], or lack access to lung function testing such as spirometry and peak flow [3]. Asthma-associated morbidity and mortality increase with older age [4]. The number of unscheduled ambulatory visits, emergency visits, and hospitalizations is high in elderly asthmatics [5]. Elderly individuals with asthma in comparison to young adults have 14-fold higher asthma-related death rates and are twice as likely to be hospitalized in a given year [6]. Death rates attributable to asthma increase exponentially after age of 65 [7], with women and particularly black women being the most affected [8]. Nonetheless, suboptimal therapeutic
The Role of Serotonin in Sleep Disordered Breathing Associated with Parkinson Disease: A Correlative [11C]DASB PET Imaging Study
Irene M. Lelieveld, Martijn L. T. M. Müller, Nicolaas I. Bohnen, Robert A. Koeppe, Ronald D. Chervin, Kirk A. Frey, Roger L. Albin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040166
Abstract: Sleep dysfunction and excessive daytime sleepiness are common in Parkinson disease (PD). Several studies suggest that PD patients exhibit high prevalence of sleep-disordered breathing (SDB). PD has a complex profile of neurochemical deficits in which abnormalities of different neurotransmitter systems may play significant and differing roles in the development of non-motor features. In the present study, we investigated whether SDB in PD is related to serotoninergic neuron degeneration. We used a cross-sectional design to assess the correlation between SDB and measures of caudal brainstem serotonin neuron integrity. Fifty one PD participants with mean disease duration of 6.0 (SD 3.7) years and mean age of 63.9 (SD 6.2) years were studied. We measured caudal brainstem serotoninergic innervation with [11C]DASB positron emission tomography (PET) imaging and striatal dopaminergic innervation with [11C]DTBZ PET imaging. SDB was assessed with polysomnography (PSG) and sleepiness with multiple sleep latency tests. Greater than half of participants exhibited PSG evidence of significant SDB; 12 participants had normal PSGs, 6 had mild SDB, 20 had moderate SDB, and 13 had severe SDB. We found no association between severity of SDB and caudal brainstem serotoninergic innervation in PD participants. Striatal dopaminergic denervation did not correlate with severity of SDB. We did find significant correlations between measures of motor function impairment and sleep quantity and quality in PD. Neither serotoninergic nor dopaminergic neuron degeneration is likely to play a major role in SDB observed in PD patients.
The re-distribution of matter in the cores of galaxy clusters
Chervin F. P. Laporte,Simon D. M. White
Physics , 2014,
Abstract: We present cosmological N-body resimulations of the assembly of the Brightest Cluster Galaxies (BCGs) in rich clusters. At $z=2$ we populate dark matter subhalos with self-gravitating stellar systems whose abundance and structure match observed high-redshift galaxies. By $z=0$, mergers have built much larger galaxies at cluster centre. Their dark matter density profiles are shallower than in corresponding dark-matter-only simulations, but their total mass density profiles (stars + dark matter) are quite similar. Differences are found only at radii where the effects of central black holes may be significant. Dark matter density slopes shallower than $\gamma=1.0$ occur for $r/r_{200} < 0.015$, close to the half-light radii of the BCGs. Our experiments support earlier suggestions that NFW-like profiles are an attractor for the hierarchical growth of structure in collisionless systems -- total mass density profiles asymptote to the solution found in dark-matter-only simulations over the radial range where mergers produce significant mixing between stars and dark matter. Simulated dark matter fractions are substantially higher in BCGs than in field ellipticals, reaching 80\% within the half-light radius. We also estimate that supermassive black hole mergers should create BCG cores as large as $r_{c}\sim 3 \,\mathrm{kpc}$. The good agreement of all these properties with recent observational studies of BCG structure suggests that dissipational processes have not played a dominant role in the assembly of the observed systems.
Estudio de 34 pacientes con incidentaloma suprarrenal
Chervin,Raúl A.; Danilowicz,Karina; Pitoia,Fabián; Gómez,Reynaldo M.; Bruno,Oscar D.;
Medicina (Buenos Aires) , 2007,
Abstract: adrenal incidentaloma, a tumor discovered unexpectedly during imaging performed for non-adrenal related causes, has become a frequent clinical concern. although in most cases they are benign and hormonally nonfunctioning, it is important to appropriately identify those few cases of malignant or hyperfunctioning lesions of surgical resolution. although several proposals for an optimal diagnostic strategy have been designed, controversy over a series of questions still persists. in the present retrospective study we analyzed 34 patients with adrenal incidentaloma. of these, 32% of the patients displayed hyperfunctioning pathologies that included subclinical cushing's syndrome in four patients, probable primary hyperaldosteronism in two, late onset congenital adrenal hyperplasia in one, adrenocortical carcinoma in one and pheochromocytoma in three. ct and/or mri permitted the identification of adenomas and were crucial to decide on surgery in two patients with nonfunctioning pheochromocytomas and in a patient carrying a primitive adrenocortical carcinoma, a diagnosis also suggested by a mixed pattern of hypersecretion of androgens and cortisol. in a diabetic and hypertensive patient with subclinical cushing's syndrome both comorbidities were solved by surgery. nonfunctioning tumors were mainly adenomas (87%) with individual cases of histoplasmosis, pseudocyst, idiopathic adrenal hyperplasia and mielolipoma. six of the eight operated patients presented malignant and/or hyperfunctioning tumors. the pathology associated with incidentalomas represents a broad spectrum of risk for patients and reaffirms the necessity for a meticulous clinical, biochemical, and imaging evaluation in order to make appropriate decisions.
Shallow Dark Matter Cusps in Galaxy Clusters
Chervin F. P. Laporte,Simon D. M. White,Thorsten Naab,Mateusz Ruszkowski,Volker Springel
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.21262.x
Abstract: We study the evolution of the stellar and dark matter components in a galaxy cluster of $10^{15} \, \rm{M_{\odot}}$ from $z=3$ to the present epoch using the high-resolution collisionless simulations of Ruszkowski & Springel (2009). At $z=3$ the dominant progenitor halos were populated with spherical model galaxies with and without accounting for adiabatic contraction. We apply a weighting scheme which allows us to change the relative amount of dark and stellar material assigned to each simulation particle in order to produce luminous properties which agree better with abundance matching arguments and observed bulge sizes at $z=3$. This permits the study of the effect of initial compactness on the evolution of the mass-size relation. We find that for more compact initial stellar distributions the size of the final Brightest Cluster Galaxy grows with mass according to $r\propto M^{2}$, whereas for more extended initial distributions, $r\propto M$. Our results show that collisionless mergers in a cosmological context can reduce the strength of inner dark matter cusps with changes in logarithmic slope of 0.3 to 0.5 at fixed radius. Shallow cusps such as those found recently in several strong lensing clusters thus do not necessarily conflict with CDM, but may rather reflect on the initial structure of the progenitor galaxies, which was shaped at high redshift by their formation process.
The Growth in Size and Mass of Cluster Galaxies since z=2
Chervin F. P. Laporte,Simon D. M. White,Thorsten Naab,Liang Gao
Physics , 2013, DOI: 10.1093/mnras/stt912
Abstract: We study the formation and evolution of Brightest Cluster Galaxies starting from a $z=2$ population of quiescent ellipticals and following them to $z=0$. To this end, we use a suite of nine high-resolution dark matter-only simulations of galaxy clusters in a $\Lambda$CDM universe. We develop a scheme in which simulation particles are weighted to generate realistic and dynamically stable stellar density profiles at $z=2$. Our initial conditions assign a stellar mass to every identified dark halo as expected from abundance matching; assuming there exists a one-to-one relation between the visible properties of galaxies and their host haloes. We set the sizes of the luminous components according to the observed relations for $z\sim2$ massive quiescent galaxies. We study the evolution of the mass-size relation, the fate of satellite galaxies and the mass aggregation of the cluster central. From $z=2$, these galaxies grow on average in size by a factor 5 to 10 of and in mass by 2 to 3. The stellar mass growth rate of the simulated BCGs in our sample is of 1.9 in the range $0.3
Maize Development: Cell Wall Changes in Leaves and Sheaths  [PDF]
Ronald D. Hatfield, Jane M. Marita
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.86083
Abstract: Developmental changes occur in maize (Zea mays L.) as it transitions from juvenile stages to the mature plant. Changes also occur as newly formed cells mature into adult cells. Maize leaf blades including the midribs and sheaths undergo cell wall changes as cells transition to fully mature cell types. As is common in grasses during cell wall maturation, the lignin in the plant tissue is acylated with p-coumarates (pCA). This work characterizes cell walls in maize that make up leaf blade, leaf midrib, and sheath tissues corresponding to tissue development. Maize plants grown in the greenhouse were harvested; leaf, leaf midrib, and sheath tissues from nodes 9 through 14 tissues were analyzed for cell wall composition. Cell wall carbohydrates varied with the type of maize tissue, but there was little change within a tissue type among the different nodes. Lignin concentrations were lowest in the leaf blade (70 - 88 g·kg-1 CW) followed by the sheath (123 - 140 g·kg-1 CW) and highest in the midrib (140 -
Nuevos mecanismos involucrados en la patogénesis de adenomas hipofisarios
Giacomini,D.; Paez-Pereda,M.; Refojo,D.; Carbia Nagashima,A.; Chervin,A.; Goldberg,V.; Arzt,E.;
Medicina (Buenos Aires) , 2003,
Abstract: we studied smad-4dn tumors generated from lactosomatotrophic gh3 cells stably transfected with a dominant negative form of smad-4 (a bone morphogenetic protein-4, bmp-4, signal co-transducer) which had reduced tumorigenicity in nude mice, but had showed a late increase in tumor size. we found that they had lost in vivo the expression of smad-4dn and had recovered c-myc expression. in accordance, bmp-4 is overexpressed and stimulates the expression of c-myc in human prolactinomas, but not in other human pituitary adenomas or normal pituitary. in adittion ici 182,780 inhibited bmp-4 stimulated c-myc expression and bmp-4 and 17b-estradiol in combination had an additive effect on gh3 cell proliferation. their action was inhibited by blocking bmp-4 with ici 182,780 or 17b-estradiol with smad-4dn. furthermore, co-immunoprecipitation studies demonstrate that smad-4 physically interacts with the era/erb. we show for the first time the role of bmp-4 in prolactinoma pathogenesis, involving a functional cross-talk bmp-4/e2.
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