86 research outputs found
On the abundance of non-cometary HCN on Jupiter
Using one-dimensional thermochemical/photochemical kinetics and transport
models, we examine the chemistry of nitrogen-bearing species in the Jovian
troposphere in an attempt to explain the low observational upper limit for HCN.
We track the dominant mechanisms for interconversion of N2-NH3 and HCN-NH3 in
the deep, hightemperature troposphere and predict the rate-limiting step for
the quenching of HCN at cooler tropospheric altitudes. Consistent with other
investigations that were based solely on time-scale arguments, our models
suggest that transport-induced quenching of thermochemically derived HCN leads
to very small predicted mole fractions of hydrogen cyanide in Jupiter's upper
troposphere. By the same token, photochemical production of HCN is ineffective
in Jupiter's troposphere: CH4-NH3 coupling is inhibited by the physical
separation of the CH4 photolysis region in the upper stratosphere from the NH3
photolysis and condensation region in the troposphere, and C2H2-NH3 coupling is
inhibited by the low tropospheric abundance of C2H2. The upper limits from
infrared and submillimeter observations can be used to place constraints on the
production of HCN and other species from lightning and thundershock sources.Comment: 56 pages, 0 tables, 6 figures. Submitted to Faraday Discussions [in
press
Pressure-Flow Characteristics of Normal and Disordered Esophageal Motor Patterns
Copyright © 2015 Elsevier Inc. All rights reserved
This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Objective
To perform pressure-flow analysis (PFA) in a cohort of pediatric patients who were referred for diagnostic manometric investigation.
Study design
PFA was performed using purpose designed Matlab-based software. The pressure-flow index (PFI), a composite measure of bolus pressurization relative to flow and the impedance ratio, a measure of the extent of bolus clearance failure were calculated.
Results
Tracings of 76 pediatric patients (32 males; 9.1 ± 0.7 years) and 25 healthy adult controls (7 males; 36.1 ± 2.2 years) were analyzed. Patients mostly had normal motility (50%) or a category 4 disorder and usually weak peristalsis (31.5%) according to the Chicago Classification. PFA of healthy controls defined reference ranges for PFI â€142 and impedance ratio â€0.49. Pediatric patients with pressure-flow (PF) characteristics within these limits had normal motility (62%), most patients with PF characteristics outside these limits also had an abnormal Chicago Classification (61%). Patients with high PFI and disordered motor patterns all had esophagogastric junction outflow obstruction.
Conclusions
Disordered PF characteristics are associated with disordered esophageal motor patterns. By defining the degree of over-pressurization and/or extent of clearance failure, PFA may be a useful adjunct to esophageal pressure topography-based classification
Pressure Flow Analysis in the Assessment of Preswallow Pharyngeal Bolus Presence in Dysphagia
Copyright © 2015 Lara Ferris et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Objectives. Preswallow pharyngeal bolus presence is evident in patients with oropharyngeal dysphagia. Pressure flow analysis (PFA) using high resolution manometry with impedance (HRMI) with AIMplot software is a method for objective interpretation of pharyngeal and upper esophageal sphincter (UES) pressures and bolus flow patterns during swallowing. This study aimed to observe alterations in PFA metrics in the event of preswallow pharyngeal bolus presence as seen on videofluoroscopy (VFSS). Methods. Swallows from 40 broad dysphagia patients and 8 controls were recorded with a HRMI catheter during simultaneous VFSS. Evidence of bolus presence and level reached prior to pharyngeal swallow onset was recorded. AIMPlot software derived automated PFA functional metrics. Results. Patients with bolus movement to the pyriform sinuses had a higher SRI, indicating greater swallow dysfunction. Amongst individual metrics, TNadImp to PeakP was shorter and flow interval longer in patient groups compared to controls. A higher pharyngeal mean impedance and UES mean impedance differentiated the two patient groups. Conclusions. This pilot study identifies specific altered PFA metrics in patients demonstrating preswallow pharyngeal bolus presence to the pyriform sinuses. PFA metrics may be used to guide diagnosis and treatment of patients with oropharyngeal dysphagia and track changes in swallow function over time
Pathophysiology of swallowing following oropharyngeal surgery for obstructive sleep apnea syndrome
This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving'.
© 2017 John Wiley & Sons, Inc. All rights reserved.
This author accepted manuscript is made available following 12 month embargo from date of publication (Dec 2017) in accordance with the publisherâs archiving policyBackground
Uvulopalatopharyngoplasty (UPPP) and coblation channeling of the tongue (CCT) are oropharyngeal surgeries used to treat obstructive sleep apnea syndrome. The extent to which UPPP and CCT affect pharyngeal swallow has not been determined. We therefore conducted a novel case series study employing highâresolution impedance manometry (HRIM) to quantify the swallowingârelated biomechanics following UPPP and/or CCT surgery.
Methods
Twelve patients who underwent UPPP+CCT or CCT only were assessed an average 2.5 years postsurgery. Swallow function data were compared with ten healthy controls. All patients completed the Sydney swallow questionnaire (SSQ). Pharyngeal pressureâflow analysis of HRIM recordings captured key distension, contractility and pressureâflow timing swallow parameters testing 5, 10, and 20 mL volumes of thin and thick fluid consistencies.
Key Results
Postoperative patients had more dysphagia symptoms with five returning abnormal SSQ scores. Swallowing was biomechanically altered compared to controls, consistent with diminished swallowing reserve, largely driven by elevated hypopharyngeal intrabolus pressure due to a reduced capacity to open the upper esophageal sphincter to accommodate larger volumes.
Conclusions & Inferences
Patients who have undergone UPPP and/or CCT surgery appear to have a deficiency in normal modulation of the swallowing mechanism and a reduced swallowing functional reserve. We speculate that these changes may become relevant in later life with the onset of ageârelated stressors to the swallowing mechanism. This case series strikes a note of caution that further studies are needed to determine the role of preoperative swallow assessment in patients undergoing UPPP and/or CCT surgery
Monomeric C-Reactive Protein Localized in the Cerebral Tissue of Damaged Vascular Brain Regions Is Associated With Neuro-Inflammation and Neurodegeneration-An Immunohistochemical Study
Monomeric C-reactive protein (mCRP) is now accepted as having a key role in modulating inflammation and in particular, has been strongly associated with atherosclerotic arterial plaque progression and instability and neuroinflammation after stroke where a build-up of the mCRP protein within the brain parenchyma appears to be connected to vascular damage, neurodegenerative pathophysiology and possibly Alzheimer's Disease (AD) and dementia. Here, using immunohistochemical analysis, we wanted to confirm mCRP localization and overall distribution within a cohort of AD patients showing evidence of previous infarction and then focus on its co-localization with inflammatory active regions in order to provide further evidence of its functional and direct impact. We showed that mCRP was particularly seen in large amounts within brain vessels of all sizes and that the immediate micro-environment surrounding these had become laden with mCRP positive cells and extra cellular matrix. This suggested possible leakage and transport into the local tissue. The mCRP-positive regions were almost always associated with neurodegenerative, damaged tissue as hallmarked by co-positivity with pTau and ÎČ-amyloid staining. Where this occurred, cells with the morphology of neurons, macrophages and glia, as well as smaller microvessels became mCRP-positive in regions staining for the inflammatory markers CD68 (macrophage), interleukin-1 beta (IL-1ÎČ) and nuclear factor kappa B (NFÎșB), showing evidence of a perpetuation of inflammation. Positive staining for mCRP was seen even in distant hypothalamic regions. In conclusion, brain injury or inflammatory neurodegenerative processes are strongly associated with mCRP localization within the tissue and given our knowledge of its biological properties, it is likely that this protein plays a direct role in promoting tissue damage and supporting progression of AD after injury.The authors extend their appreciations to the deputyship for Research & Innovation, Ministry of Education in Saudi Arabia for funding this research work through the project number (lFP-2020-36). The authors would also like to thank Deanship of Scientific Research at Majmaah University, Al Majmaah-11952, Saudi Arabia for supporting this work. This work was supported from a grant from the Competitiveness Operational programme 2014â2020: C-reactive protein therapy for stroke-associated dementia: ID_P_37_674, My SMIS code:103432 contract 51/05.09.2016
Pressure-Flow Analysis for the Assessment of Pediatric Oropharyngeal Dysphagia
This is the authorsâ version of an article published in Journal of Pediatrics. The original publication is available by subscription at: http://dx.doi.org/10.1016/j.jpeds.2016.06.032 Licensed under the the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/. This author accepted manuscript is made available following 12 month embargo from date of publication (1 Aug 2016) in accordance with the publisher's copyright policy.Objectives
Pharyngeal High Resolution Manometry with Impedance (HRIM) was performed in a heterogeneous group of children with signs of oropharyngeal dysphagia (OPD). The aim of this study was to determine which objective pressure-impedance measures of pharyngeal swallowing function correlated with clinically assessed severity of OPD symptoms.
Study Design
Forty five pediatric OPD patients and 34 non-OPD controls were recruited and up to 5 liquid bolus swallows were recorded using a solid state HRIM catheter. Individual measures of pharyngeal and upper esophageal sphincter (UES) function and a Swallow Risk Index composite score were derived for each swallow, and averaged data for OPD patients were compared against those of non-OPD controls. Clinical severity of OPD symptoms and oral feeding competency was based on the validated Dysphagia Disorders Survey (DDS) and Functional Oral Intake Scale.
Results
Those objective measures that were markers of UES relaxation, UES opening and pharyngeal flow resistance, differentiated patients with and without OPD symptoms. Patients demonstrating abnormally high pharyngeal intra-bolus pressures and high UES resistance, markers of outflow obstruction, were most likely to have overt DDS signs and symptoms (Odds Ratio 9.24, p=0.05, and 9.7, p = 0.016, respectively).
Conclusion
Pharyngeal motor patterns can be recorded in children using HRIM and pharyngeal function can be objectively defined using pressure-impedance measures. Objective measurements suggest that pharyngeal dysfunction is common in children with clinical signs of OPD. A key finding of this study was evidence of markers of restricted UES opening
Upper Gastrointestinal Function in Morbidly Obese Adolescents before and Six Months after Gastric Banding
âThis is a pre-print of an article published in Obesity Surgery. The final authenticated version is available online at: https://doi.org/10.1007/s11695-017-3000-3â.
© Springer Science+Business Media, LLC 2017
This author accepted manuscript is made available following 12 month embargo from date of publication (Nov 2017) in accordance with the publisherâs archiving policyBackground
The effects of laparoscopic adjustable gastric band (LAGB) placement on upper gastrointestinal tract function in obese adolescents are unknown. Therefore, our aim was to determine the short-term effects of LAGB on esophageal motility, gastroesophageal reflux, gastric emptying, appetite-regulatory hormones, and perceptions of post-prandial hunger and fullness.
Methods
This study was part of a prospective cohort study (March 2009âDecember 2015) in one tertiary referral hospital. The study included obese adolescents (14â18 years) with a body mass index (BMI) > 40 (or â„ 35 with comorbidities). Gastric emptying was assessed by 13C-octanoic acid breath test, pharyngeal, and esophageal motor function by high-resolution manometry with impedance (HRIM), and appetite and other perceptions using 100-mm visual analogue scales. Dysphagia symptoms were scored using a Dakkak questionnaire. Data were compared pre- and post-LAGB placement and at a 6-month follow-up.
Results
Based upon analysis of 15 adolescents, at the 6-month follow-up, LAGB placement: (i) led to a significant reduction in weight and BMI; (ii) increased fullness and decreased hunger post-meal; (iii) increased symptoms of dysphagia after solid food; and, despite these effects, (iv) caused little or no changes to appetite hormones, while (v) effects on gastric emptying, esophageal motility, esophageal bolus transport, and esophageal emptying were not significant.
Conclusion
In adolescents, LAGB improved BMI and altered the sensitivity to nutrients without significant effects on upper gastrointestinal tract physiology at the 6-month follow-up
Monomeric C-reactive protein localized in the cerebral tissue of damaged vascular brain regions is associated with neuro-inflammation and neurodegeneration - an immunohistochemical study
Monomeric C-reactive protein (mCRP) is now accepted as having a key role in modulating inflammation and in particular, has been strongly associated with atherosclerotic arterial plaque progression and instability and neuroinflammation after stroke where a build-up of the mCRP protein within the brain parenchyma appears to be connected to vascular damage, neurodegenerative pathophysiology and possibly Alzheimer's Disease (AD) and dementia. Here, using immunohistochemical analysis, we wanted to confirm mCRP localization and overall distribution within a cohort of AD patients showing evidence of previous infarction and then focus on its co-localization with inflammatory active regions in order to provide further evidence of its functional and direct impact. We showed that mCRP was particularly seen in large amounts within brain vessels of all sizes and that the immediate micro-environment surrounding these had become laden with mCRP positive cells and extra cellular matrix. This suggested possible leakage and transport into the local tissue. The mCRP-positive regions were almost always associated with neurodegenerative, damaged tissue as hallmarked by co-positivity with pTau and ÎČ-amyloid staining. Where this occurred, cells with the morphology of neurons, macrophages and glia, as well as smaller microvessels became mCRP-positive in regions staining for the inflammatory markers CD68 (macrophage), interleukin-1 beta (IL-1ÎČ) and nuclear factor kappa B (NFÎșB), showing evidence of a perpetuation of inflammation. Positive staining for mCRP was seen even in distant hypothalamic regions. In conclusion, brain injury or inflammatory neurodegenerative processes are strongly associated with mCRP localization within the tissue and given our knowledge of its biological properties, it is likely that this protein plays a direct role in promoting tissue damage and supporting progression of AD after injury
Scale-up of HIV Treatment Through PEPFAR: A Historic Public Health Achievement
Since its inception in 2003, the US Presidentâs Emergency Plan for AIDS Relief (PEPFAR) has been an important driving force behind the global scale-up of HIV care and treatment services, particularly in expansion of access to antiretroviral therapy. Despite initial concerns about cost and feasibility, PEPFAR overcame challenges by leveraging and coordinating with other funders, by working in partnership with the most affected countries, by supporting local ownership, by using a public health approach, by supporting task-shifting strategies, and by paying attention to health systems strengthening. As of September 2011, PEPFAR directly supported initiation of antiretroviral therapy for 3.9 million people and provided care and support for nearly 13 million people. Benefits in terms of prevention of morbidity and mortality have been reaped by those receiving the services, with evidence of societal benefits beyond the anticipated clinical benefits. However, much remains to be accomplished to achieve universal access, to enhance the quality of programs, to ensure retention of patients in care, and to continue to strengthen health systems
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