Adrenergetic modulation of the intrinsic myogenic activity of peripheral diaphragmatic lymphatics.

The diaphragmatic lymphatic system drains fluids and solutes from diaphragmatic interstitium and from the pleural and peritoneal cavities. Initial lymphatics, devoid of smooth muscle cells (SMCs) in their walls, join into long linear vessels or complex loops, formed at the confluence of linear vessels. Both linear vessels and loops, visible below the pleural and peritoneal mesothelia over the diaphragmatic dome, may be segmented in functional units, called lymphangions, separated by intraluminal valves, which ensure unidirectional lymph flow. Lymph progression within the diaphragmatic lymphatic vessels is due to an hydraulic pressure gradient of between adjacent lymphatic segments whose generation and maintenance depends upon a system of extrinsic and intrinsic pumps. Extrinsic pumping is mainly due to the movement of the surrounding tissues which causes the contraction/expansion of the vessel, while the intrinsic pumping mechanism is due to the rhythmic contraction of the smooth muscle cells surrounding the wall of the lymphangions. Extrinsic pumping prevails in lymphatics of the medial diaphragm, while lymphatic loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally. Lymph propulsion within the most peripheral diaphragmatic lymphatics depends upon tissue displacements and contraction of smooth muscle cells that surround the collecting lymphatics. The aim of the present work was to investigate, in actively contracting sites of peripheral diaphragmatic lymphatic vessels, the contribution of single strokes and valves opening/closing dynamics to lymph propulsion, and to analyze how this phenomenon is modulated by epinephrine. Anaesthetized rats received an intraperitoneal injection of a mixture of FITC-conjugated dextrans and TRITC-labeled microspheres (0.1-1 m diameter). After passive lymphatic vessels loading, microspheres movement were video recorded ex-vivo in excised pieces of diaphragm, kept superfused with warmed oxygenated Tyrode’s solution in a flow chamber on the stage of an upright microscope. Instantaneous and mean microsphere velocities were derived from microsphere trajectories along with vessel diameter changes due to spontaneous active strokes. Data obtained show that active strokes exert a distance-dependent effect on microspheres progression from the contracting site. Their velocity profile results parabolic with a peak velocity of about 96 μm/sec. In the presence of intraluminal valves, microspheres show an oscillatory trajectory on the proximal side and monotonic outward directed flow on the distal side of the valve. Epinephrine administration has opposite effects in linear vessels and lymphatic loops: in particular, epinephrine determines an increase in contraction frequency of about 3 bpm and a greater distance traveled by microspheres in loops and an impairment of spontaneous activity in linear vessels

Adrenergetic modulation of the intrinsic myogenic activity of peripheral diaphragmatic lymphatics.

The diaphragmatic lymphatic system drains fluids and solutes from diaphragmatic interstitium and from the pleural and peritoneal cavities. Initial lymphatics, devoid of smooth muscle cells (SMCs) in their walls, join into long linear vessels or complex loops, formed at the confluence of linear vessels. Both linear vessels and loops, visible below the pleural and peritoneal mesothelia over the diaphragmatic dome, may be segmented in functional units, called lymphangions, separated by intraluminal valves, which ensure unidirectional lymph flow. Lymph progression within the diaphragmatic lymphatic vessels is due to an hydraulic pressure gradient of between adjacent lymphatic segments whose generation and maintenance depends upon a system of extrinsic and intrinsic pumps. Extrinsic pumping is mainly due to the movement of the surrounding tissues which causes the contraction/expansion of the vessel, while the intrinsic pumping mechanism is due to the rhythmic contraction of the smooth muscle cells surrounding the wall of the lymphangions. Extrinsic pumping prevails in lymphatics of the medial diaphragm, while lymphatic loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally. Lymph propulsion within the most peripheral diaphragmatic lymphatics depends upon tissue displacements and contraction of smooth muscle cells that surround the collecting lymphatics. The aim of the present work was to investigate, in actively contracting sites of peripheral diaphragmatic lymphatic vessels, the contribution of single strokes and valves opening/closing dynamics to lymph propulsion, and to analyze how this phenomenon is modulated by epinephrine. Anaesthetized rats received an intraperitoneal injection of a mixture of FITC-conjugated dextrans and TRITC-labeled microspheres (0.1-1 \uf06dm diameter). After passive lymphatic vessels loading, microspheres movement were video recorded ex-vivo in excised pieces of diaphragm, kept superfused with warmed oxygenated Tyrode\u2019s solution in a flow chamber on the stage of an upright microscope. Instantaneous and mean microsphere velocities were derived from microsphere trajectories along with vessel diameter changes due to spontaneous active strokes. Data obtained show that active strokes exert a distance-dependent effect on microspheres progression from the contracting site. Their velocity profile results parabolic with a peak velocity of about 96 \u3bcm/sec. In the presence of intraluminal valves, microspheres show an oscillatory trajectory on the proximal side and monotonic outward directed flow on the distal side of the valve. Epinephrine administration has opposite effects in linear vessels and lymphatic loops: in particular, epinephrine determines an increase in contraction frequency of about 3 bpm and a greater distance traveled by microspheres in loops and an impairment of spontaneous activity in linear vessels

Adrenergetic modulation of the intrinsic myogenic activity of peripheral diaphragmatic lymphatics.

The diaphragmatic lymphatic system drains fluids and solutes from diaphragmatic interstitium and from the pleural and peritoneal cavities. Initial lymphatics, devoid of smooth muscle cells (SMCs) in their walls, join into long linear vessels or complex loops, formed at the confluence of linear vessels. Both linear vessels and loops, visible below the pleural and peritoneal mesothelia over the diaphragmatic dome, may be segmented in functional units, called lymphangions, separated by intraluminal valves, which ensure unidirectional lymph flow. Lymph progression within the diaphragmatic lymphatic vessels is due to an hydraulic pressure gradient of between adjacent lymphatic segments whose generation and maintenance depends upon a system of extrinsic and intrinsic pumps. Extrinsic pumping is mainly due to the movement of the surrounding tissues which causes the contraction/expansion of the vessel, while the intrinsic pumping mechanism is due to the rhythmic contraction of the smooth muscle cells surrounding the wall of the lymphangions. Extrinsic pumping prevails in lymphatics of the medial diaphragm, while lymphatic loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally. Lymph propulsion within the most peripheral diaphragmatic lymphatics depends upon tissue displacements and contraction of smooth muscle cells that surround the collecting lymphatics. The aim of the present work was to investigate, in actively contracting sites of peripheral diaphragmatic lymphatic vessels, the contribution of single strokes and valves opening/closing dynamics to lymph propulsion, and to analyze how this phenomenon is modulated by epinephrine. Anaesthetized rats received an intraperitoneal injection of a mixture of FITC-conjugated dextrans and TRITC-labeled microspheres (0.1-1 m diameter). After passive lymphatic vessels loading, microspheres movement were video recorded ex-vivo in excised pieces of diaphragm, kept superfused with warmed oxygenated Tyrode’s solution in a flow chamber on the stage of an upright microscope. Instantaneous and mean microsphere velocities were derived from microsphere trajectories along with vessel diameter changes due to spontaneous active strokes. Data obtained show that active strokes exert a distance-dependent effect on microspheres progression from the contracting site. Their velocity profile results parabolic with a peak velocity of about 96 μm/sec. In the presence of intraluminal valves, microspheres show an oscillatory trajectory on the proximal side and monotonic outward directed flow on the distal side of the valve. Epinephrine administration has opposite effects in linear vessels and lymphatic loops: in particular, epinephrine determines an increase in contraction frequency of about 3 bpm and a greater distance traveled by microspheres in loops and an impairment of spontaneous activity in linear vessels

Structural equation model for estimating risk factors in type 2 diabetes mellitus in a Middle Eastern setting: evidence from the STEPS Qatar.

AIMS: Understanding type 2 diabetes mellitus is critical for designing effective diabetes prevention policies in Qatar and the Middle East. METHODS: Using the Qatar 2012 WHO STEPwise approach to surveillance survey, a subsample of 1224 Qatari participants aged 18-64 years was selected. Subjects had their fasting blood glucose levels tested, had not been diagnosed with or treated for diabetes, had a fasting time >12 hours and were not pregnant. We applied a hypothesized structural equation model (SEM) to assess sociodemographic, behavioral, anthropometric and metabolic variables affecting persons with type 2 diabetes mellitus. RESULTS: There is a direct effect of triglyceride levels (0.336) and body mass index (BMI) (0.164) on diabetes status. We also found that physical activity levels negatively affect BMI (-0.148) and positively affect high-density lipoprotein (HDL) (0.106); sociodemographic background negatively affects diet (-0.522) and BMI (-0.352); HDL positively affects total cholesterol (0.230) and has a negative effect on BMI (-0.108), triglycerides (-0.128) and waist circumference (-0.104). Diet has a positive effect on triglycerides (0.281) while family history of diabetes negatively affects total cholesterol (-0.104). BMI has a positive effect on waist circumference (0.788) and mediates the effects of physical activity over diabetes status (-0.028). BMI also mediates the effects that sociodemographic factors (-0.058) and physical activity (-0.024) have on diabetes status. BMI and HDL (-0.002) together mediate the effect of physical activity on diabetes status and similarly HDL and tryglycerides (-0.005) also mediate the effect of physical activity on diabetes status. Finally diet and tryglycerides mediate the effects that sociodemographic factors have on diabetes status (-0.049). CONCLUSIONS: This study's main finding is that triglyceride levels and BMI are the main variables directly affecting diabetes status in the Qatari population

Clinical and Imaging Assessment of Metal on Metal Hip Patients

A high failure rate of metal-on-metal (MoM) hip implants prompted regulatory authorities to issue worldwide product recalls. The cause for their failure and decisions surrounding the need for revision is complex due to poor understanding of the toxic effects of metal debris. In addition to local soft tissue destruction, circulating cobalt can cause rare but fatal cardiotoxicity. This thesis describes the detection of metal cobalt-chromium within the liver of a patient with highly elevated blood cobalt (587ppb) using novel MRI imaging techniques, validated by liver biopsy and micro x-ray fluorescence. The prevalence of tissue metal deposition and potential cardiotoxic effects were assessed through a prospective case controlled cohort study. Ninety patients were recruited into three age and gender-matched groups according to blood metal levels. All underwent detailed cardiovascular and liver phenotyping using MRI (for myocardial volumes and function, T2*, T1 and Extra-Cellular Volume mapping), echocardiography, and blood biomarker sampling. T2* is a novel MRI biomarker of tissue metal deposition. Blood cobalt levels among the cohort ranged 0.1 to 118ppb, which is still seen in patients presenting for clinical follow-up. No significant between-group differences were found for cardiac volume or function, nor was there any difference in tissue characterization using T1, T2* and ECV. Higher blood cobalt levels did not translate to increased metal deposition within the heart or liver.The application of these results were analsyed through a multi-disciplianary team setting designed to aid complex decisions of who, when and how to treat MoM patients surgically. By analysis of MDT recommendations compared to the treatment undertaken it was demonstrated that an MDT approach is an acceptable evidence-based aid to decision-making.This thesis concludes that cobalt tissue deposition can be detected using non-invasive MRI techniques, however metal deposition is not commonly seen with blood cobalt levels upto 118ppb with reassuringly little cardiotoxic effects. These results help reassure clinicians managing MoM patients through an MDT approach

Coronary Angiography

In the intervening 10 years tremendous advances in the field of cardiac computed tomography have occurred. We now can legitimately claim that computed tomography angiography (CTA) of the coronary arteries is available. In the evaluation of patients with suspected coronary artery disease (CAD), many guidelines today consider CTA an alternative to stress testing. The use of CTA in primary prevention patients is more controversial in considering diagnostic test interpretation in populations with a low prevalence to disease. However the nuclear technique most frequently used by cardiologists is myocardial perfusion imaging (MPI). The combination of a nuclear camera with CTA allows for the attainment of coronary anatomic, cardiac function and MPI from one piece of equipment. PET/SPECT cameras can now assess perfusion, function, and metabolism. Assessing cardiac viability is now fairly routine with these enhancements to cardiac imaging. This issue is full of important information that every cardiologist needs to now

Park Agency Social Media Communication During the COVID-19 Crisis

The COVID-19 pandemic has affected all industries and organizations, including park agencies. There is a lack of research on how park agencies utilize Twitter during times of crisis, specifically during the COVID-19 pandemic. How park agencies communicate with the public and how they use their social media has not been extensively studied. In addition, the coronavirus pandemic is a novel management issue for these agencies, and there has been no empirical analysis in the ways in which information is being communicated to the public or how that information is being perceived. This study aims to better understand park agency response to COVID-19 through a literature review, to explore how social media is used as communication tool related to COVID-19 by park agencies, to use NVivo and NCapture software to assess the content of park agency tweets, and to provide recommendations for park agencies in future times of crisis to enhance communication effectiveness using social media. Qualitative analysis methods are used, guided by grounded theory and content analysis. NVivo and NCapture software was utilized to gather 8045 tweets from 21 Canadian park agencies, individual national parks, and individual provincial parks. In addition, the United States (U.S.) National Park Service (NPS) was also examined to compare social media response from both Canadian and American national park agencies. Those tweets were then coded into three major categories: pre COVID-19, COVID-19, and non COVID-19. Coding the tweets and organizing them thematically through inductive reasoning was done within the software. Chi-squared analyses were conducted to determine if there were any statistically significant differences between the various agencies and themes found within the data. The key findings were that messaging frequency regarding COVID-19 was reduced after the summer months due to peak season ending, even though the pandemic was in full swing and the number of cases was rising. There was a statistically significant difference found between the themes tweeted about by Parks Canada and the U.S. NPS in terms of frequency. Geographically, there was a statistically significant difference between themes tweeted about by various Canadian national and provincial parks, referencing the lack of standardized messaging and cohesiveness when it comes to social media content across the country. In addition, there was a lack of promotion of virtual programming from Canadian individual national and provincial parks, contrary to the U.S. NPS. From this study, it can be concluded that parks and protected area agencies should work closer with other departments, such as the health department, to potentially get the necessary messaging across. It is also recommended that capacity in parks needs to increase through virtual programming, as there have been successful cases of this already in other industries such as zoos and mental health institutes. Public access to parks and protected areas provides mental and physical health benefits, and virtual engagements can provide an alternative to this throughout the COVID-19 pandemic and future crises. Finally, parks and protected area agencies can benefit from a more standardized social media strategy, especially during a crisis, to better inform and update the public

American Society of Hematology 2020 guidelines for sickle cell disease: Prevention, diagnosis, and treatment of cerebrovascular disease in children and adults

BACKGROUND: Central nervous system (CNS) complications are among the most common, devastating sequelae of sickle cell disease (SCD) occurring throughout the lifespan.OBJECTIVE: These evidence-based guidelines of the American Society of Hematology are intended to support the SCD community in decisions about prevention, diagnosis, and treatment of the most common neurological morbidities in SCD.METHODS: The Mayo Evidence-Based Practice Research Program supported the guideline development process, including updating or performing systematic evidence reviews. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE evidence-to-decision frameworks, to assess evidence and make recommendations.RESULTS: The panel placed a higher value on maintaining cognitive function than on being alive with significantly less than baseline cognitive function. The panel developed 19 recommendations with evidence-based strategies to prevent, diagnose, and treat CNS complications of SCD in low-middle- and high-income settings.CONCLUSIONS: Three of 19 recommendations immediately impact clinical care. These recommendations include: use of transcranial Doppler ultrasound screening and hydroxyurea for primary stroke prevention in children with hemoglobin SS (HbSS) and hemoglobin Sβ0 (HbSβ0) thalassemia living in low-middle-income settings; surveillance for developmental delay, cognitive impairments, and neurodevelopmental disorders in children; and use of magnetic resonance imaging of the brain without sedation to detect silent cerebral infarcts at least once in early-school-age children and once in adults with HbSS or HbSβ0 thalassemia. Individuals with SCD, their family members, and clinicians should become aware of and implement these recommendations to reduce the burden of CNS complications in children and adults with SCD.</p