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Search Results: 1 - 10 of 184743 matches for " Richard E. Slavin "
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Segmental arterial mediolysis: A clinical-pathologic review, its role in fibromuscular dysplasia and description and differential diagnosis of the masquerader-muscular artery cystic necrosis  [PDF]
Richard E. Slavin
World Journal of Cardiovascular Diseases (WJCD) , 2013, DOI: 10.4236/wjcd.2013.31013

Segmental arterial mediolysis (SAM) is an uncommon non-inflammatory iatrogenic arteriopathy caused by alpha-1 adrenergic agonists or Beta-2 agonists able to release norepinephrine from the peripheral nervous system. Causative agents include adrenergic agonists used to control blood pressure, B-2 tocolytic agonists, and ractopamine used as a repartitioning agent in animal husbandry. The liberated norepinephrine both injures and stimulates a robust reparative response in the muscular arteries in the abdomen, brain base, and coronary arteries. This response may be augmented by endothelin-1 formed in the arterial adventitia. Three types of arterial lesions develop in the injurious stage: 1) apoptotic induced mediolysis, 2) separation of the outer media from the adventitia and 3) the formation of arterial gaps. The latter enlarge, particularly in elderly patients, to form gap-aneurysms complicated by dissections and dissecting an- eurysms that when ruptured cause the calamitous hemorrhages that clinically announce SAM. The other types of injury remain clinically silent but with repair develop sequelae and can metamorphose into fibromuscular dysplasia. The sequelae are mainly asymptomatic but may cause arterial stenosis and ischemic lesions. The definitive diagnosis of SAM re- quires histological conformation but misinterpreta- tion of smooth muscle vacuolar change has caused di- agnostic errors. Muscular artery cystic necrosis a newly named non-inflammatory muscular artery ar- teriopathy may be confused with SAM both clinically and pathologically. This arteriopathy represents the muscular artery equivalent of cystic media necrosis of the elastic arteries since it exhibits similar morphol- ogic features and can occur concomitantly with this entity. Adrenergic agents to counter hemorrhagic shock in SAM are contraindicated since they may intensify injury and create new lesions. The use of norepinehrine antagonists introduces a new, but as yet untested, treatment option for SAM.

Segmental arterial mediolysis, reparative phase: An analysis and case report showing conversion to fibromuscular dysplasia with renal infarction  [PDF]
Richard E. Slavin, Julian del Cerro Gonzalez, Jose Manuel Machin, Angel Robles, Rita Maria Regojo, Marie Luisa Diez
World Journal of Cardiovascular Diseases (WJCD) , 2014, DOI: 10.4236/wjcd.2014.42009

Segmental arterial mediolysis (SAM), an uncommon arteriopathy putatively caused by norepinephrine released by alpha-1 adrenergic agonists or some Beta-2 agonists capable of releasing norepinephrine from the peripheral sympathetic nervous system potentially can present ischemic and organ injury symptoms caused by sequelae created in its reparative phase in lieu of catastrophic hemorrhages announced in its injurious phase. The case documents this presentation—the patient presenting renal infarcts and ischemic lesions causing abdominal angina, hypertension and a nephrectomy event developing 10 years after prolonged ritodrine treatment for premature labor. This agent may have directly caused SAM or sensitized the patient to agonists causing SAM encountered at a latter date. A variety of lesions derived from injurious phase arterial injuries characterize reparative phase SAM. All were encountered in a hilar branch of the resected renal artery. These included side-by-side sequela aneurysms grossly forming a large fusiform aneurysm, granulation tissue filling adventitial medial tear spaces in which a dissecting hematomas developed, medial muscle loss centered to the outer media repaired with fibrous tissue, arterial stenosis created by reparative intimal plaques, and arterial thrombo-embolism. These lesions were mirrored in accompanying radiologic studies. The accompanying renal vein exhibited changes consistent with repair of the spastic venous angiopathy that often accompanies abdominal SAM. This angiopathy, putatively induced by Endothelin-1, suggested that this agent played a role in the genesis of the arterial lesions. Angiographic resolution of non-treated sequelae occurred in 5 months either spontaneously or due to treatment with bosentem. Conclusions: The histologic and angiographic changes demonstrate that the clinical onset of reparative SAM may be significantly delayed to produce ischemic lesions, renal infarction and in this case report, medial fibromuscular dysplasia in the hilar branch of the renal artery.

Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring
Eli Dwek,Richard G. Arendt,Patrice Bouchet,David N. Burrows,Peter Challis,I. John Danziger,James M. De Buizer,Robert D. Gehrz,Sangwook Park,Elisha F. Polomski,Jonathan D. Slavin,Charles E. Woodward
Physics , 2010, DOI: 10.1088/0004-637X/722/1/425
Abstract: We have used the Spitzer satellite to monitor the mid-IR evolution of SN 1987A over a 5 year period spanning the epochs between days 6000 and 8000 since the explosion. The supernova (SN) has evolved into a supernova remnant (SNR) and its radiative output is dominated by the interaction of the SN blast wave with the pre-existing equatorial ring (ER). The mid-IR spectrum is dominated by emission from ~180 K silicate dust, collisionally-heated by the hot X-ray emitting gas with a temperature and density of ~5x10^6 K and 3x10^4 cm-3, respectively. The mass of the radiating dust is ~1.2x10^(-6) Msun on day 7554, and scales linearly with IR flux. The infrared to soft-X-ray flux ratio is roughly constant with a value of 2.5. Gas-grain collisions therefore dominate the cooling of the shocked gas. The constancy of of this ratio suggests that very little grain processing or gas cooling have occurred throughout this epoch. The shape of the dust spectrum remained unchanged during the observations while the total flux increased with a time dependence of t^(0.87), t being the time since the first encounter between the blast wave and the ER. These observations are consistent with the transitioning of the blast wave from free expansion to a Sedov phase as it propagates into the main body of the ER.
Current algorithm for the surgical treatment of facial pain
Konstantin V Slavin, Hrachya Nersesyan, Mustafa E Colpan, Naureen Munawar
Head & Face Medicine , 2007, DOI: 10.1186/1746-160x-3-30
Abstract: Our treatment algorithm is based on taking into account underlying pathological processes, the anatomical distribution of pain, pain characteristics, the patient's age and medical condition, associated medical problems, the history of previous surgical interventions, and, in some cases, the results of psychological evaluation. The treatment modalities involved in this algorithm include diagnostic blocks, peripheral denervation procedures, craniotomy for microvascular decompression of cranial nerves, percutaneous rhizotomies using radiofrequency ablation, glycerol injection, balloon compression, peripheral nerve stimulation procedures, stereotactic radiosurgery, percutaneous trigeminal tractotomy, and motor cortex stimulation. We recommend that some patients not receive surgery at all, but rather be referred for other medical or psychological treatment.Our algorithmic approach was used in more than 100 consecutive patients with medically intractable facial pain. Clinical evaluations and diagnostic workups were followed in each case by the systematic choice of the appropriate intervention. The algorithm has proved easy to follow, and the recommendations include the identification of the optimal surgery for each patient with other options reserved for failures or recurrences. Our overall success rate in eliminating facial pain presently reaches 96%, which is higher than that observed in most clinical series reported to dateThis treatment algorithm for the intractable facial pain appears to be effective for patients with a wide variety of painful conditions and may be recommended for use in other institutions.The term "facial pain" encompasses variety of clinical conditions ranging from very common (such as headaches and myofascial pain syndromes) to less common (trigeminal neuralgia – TN) and quite rare (glossopharyngeal neuralgia – GPN) (Table 1). Although clinical presentation of some of these conditions overlaps, the treatment approaches differ significantly based o
Principal Component Analysis of EBT2 Radiochromic Film for Multichannel Film Dosimetry  [PDF]
Richard E. Wendt III
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2014, DOI: 10.4236/ijmpcero.2014.33021

Radiochromic film with a dye incorporated into the radiation sensitive layer [Gafchromic EBT2, Ashland, Inc.] may be digitized by a color transparency scanner, digitally processed, and calibrated so that a digital image in units of radiation absorbed dose is obtained. A transformation from raw scanner values to dose values was developed based upon a principal component analysis of the optical densities of the red, green and blue channels of the color image of a dose of 0.942 Gy delivered by a Sr-90/Y-90 disk-shaped source. In the order of increasing eigenvalue, the three eigenimages of the principal component analysis contained, by visual inspection, 1) mainly noise; 2) mainly a pattern of irregular streaks; and 3) most of the expected dose information along with some of the same background streaking that predominated in the second eigenimage. The combination of the second and third eigenimages that minimized the background streaking was converted into a transformation of the red, green and blue channels optical densities and applied to films with a range of doses from 0 to 63.7 Gy. The curve of dose vs. processed optical density was fit by a two-phase association curve. This processing was applied to a film exposed from its edge by a different Y-90 source in a configuration that was modeled by Monte Carlo simulation. The depth-dose curves of the measurement and simulation agree closely, suggesting that this approach is a valid method of processing EBT2 radiochromic film into maps of radiation absorbed dose.

Fiber and Prebiotics: Mechanisms and Health Benefits
Joanne Slavin
Nutrients , 2013, DOI: 10.3390/nu5041417
Abstract: The health benefits of dietary fiber have long been appreciated. Higher intakes of dietary fiber are linked to less cardiovascular disease and fiber plays a role in gut health, with many effective laxatives actually isolated fiber sources. Higher intakes of fiber are linked to lower body weights. Only polysaccharides were included in dietary fiber originally, but more recent definitions have included oligosaccharides as dietary fiber, not based on their chemical measurement as dietary fiber by the accepted total dietary fiber (TDF) method, but on their physiological effects. Inulin, fructo-oligosaccharides, and other oligosaccharides are included as fiber in food labels in the US. Additionally, oligosaccharides are the best known “prebiotics”, “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-bring and health.” To date, all known and suspected prebiotics are carbohydrate compounds, primarily oligosaccharides, known to resist digestion in the human small intestine and reach the colon where they are fermented by the gut microflora. Studies have provided evidence that inulin and oligofructose (OF), lactulose, and resistant starch (RS) meet all aspects of the definition, including the stimulation of Bifidobacterium, a beneficial bacterial genus. Other isolated carbohydrates and carbohydrate-containing foods, including galactooligosaccharides (GOS), transgalactooligosaccharides (TOS), polydextrose, wheat dextrin, acacia gum, psyllium, banana, whole grain wheat, and whole grain corn also have prebiotic effects.
Best constants for a family of Carleson sequences
Leonid Slavin
Mathematics , 2014,
Abstract: We consider a general family of Carleson sequences associated with dyadic $A_2$ weights and find sharp -- or, in one case, simply best known -- upper and lower bounds for their Carleson norms in terms of the $A_2$-characteristic of the weight. The results obtained make precise and significantly generalize earlier estimates by Wittwer, Vasyunin, Beznosova, and others. We also record several corollaries, one of which is a range of new characterizations of dyadic $A_2.$ Particular emphasis is placed on the relationship between sharp constants and optimizing sequences of weights; in most cases explicit optimizers are constructed. Our main estimates arise as consequences of the exact expressions, or explicit bounds, for the Bellman functions for the problem, and the paper contains a measure of Bellman-function innovation.
The John--Nirenberg constant of ${\rm BMO}^p,$ $1\le p\le 2$
Leonid Slavin
Mathematics , 2015,
Abstract: We compute the exact John--Nirenberg constant of ${\rm BMO}^p((0,1))$ for $1\le p\le 2,$ which has been known only for $p=1$ and $p=2.$ We also show that this constant is attained in the weak-type John--Nirenberg inequality and obtain a sharp lower estimate for the distance in ${\rm BMO}^p$ to $L^\infty.$ These results rely on sharp $L^p$- and weak-type estimates for logarithms of $A_\infty$ weights, which in turn use the exact expressions for the corresponding Bellman functions.
Treating rhinitis in the older population: special considerations
Raymond G Slavin
Allergy, Asthma & Clinical Immunology , 2009, DOI: 10.1186/1710-1492-5-9
Abstract: Rhinitis is a common and bothersome condition in the elderly. Despite its importance, little attention is paid in the general medical literature. In the most recently published highly regarded geriatric text, rhinitis is not included in the index whereas rhinophyma is [1].The number of Americans older than 65 years of age will increase from 35 million to 86 million by the year 2050 [2]. While the exact number of elderly patient with rhinitis is not known, it is believed that 40% of the general population experiences nasal symptoms [3]. It would be safe to say that the many changes that occur in the connective tissue and vasculature of the nose predisposes aging individuals to chronic rhinitis making the percentage of the elderly with nasal symptoms significantly higher than the general population [4].The elderly have generalized decrease in body water content and, along with a degeneration of mucous-secreting glands; the effectiveness of the mucociliary system is reduced, resulting in symptoms of nasal stuffiness. In addition, a decrease in nasal blood flow leads to atrophy and drying of the nasal mucous membrane and increased mucous viscosity. Structural changes in the nose with age include atrophy of the collagen fibers and loss of elastic fibers in the dermis. Weakening of the upper and lower nasal cartilage, retraction of the nasal columella, and downward rotation of the nasal tip contribute to an increase in nasal airway resistance [3].This article will deal with the special considerations of treating rhinitis in the older population. Appendix 1 lists the specific factors that may affect general medical treatment in the elderly.The elderly patient is frequently being treated for a variety of medical conditions with a number of medications. The more medications that are prescribed the less likely the patient is to comply.Aside from complying with directions for a large number of medications, the elderly patient frequently has cognitive dysfunction with a resulta
No effect of 14 day consumption of whole grain diet compared to refined grain diet on antioxidant measures in healthy, young subjects: a pilot study
Lynda Enright, Joanne Slavin
Nutrition Journal , 2010, DOI: 10.1186/1475-2891-9-12
Abstract: Twenty healthy subjects took part in a randomized, crossover dietary intervention study. Subjects consumed either a refined grain or whole grain diet for 14 days and then the other diet for the next 14 days. Male subjects consumed 8 servings of grains per day and female subjects consumed 6 servings of grains per day. Blood and urine samples were collected at the end of each diet. Antioxidant measures included oxygen radical absorbance capacity (ORAC) in blood, and isoprostanes and thiobarbituric acid reactive substances (TBARS) in urine.The whole grain diet was significantly higher in dietary fiber, vitamin B6, folate, selenium, copper, zinc, iron, magnesium and cystine compared to the refined grain diet. Despite high intakes of whole grains, no significant differences were seen in any of the antioxidant measures between the refined and whole grain diets.No differences in antioxidant measures were found when subjects consumed whole grain diets compared to refined grain diets.Epidemiological evidence supports that diets high in whole grain foods decrease risk of chronic diseases including coronary heart disease, obesity, type 2 diabetes, and many forms of cancer [1]. Whole grain intake is also linked to biomarkers of disease risk, including an inverse association of whole grain intake to incident hypertension [2]. Unfortunately, in the United States only 1% of individuals consume the recommended three servings of whole grain products per day, and approximately 20% consume virtually no whole grain products [1].There are several potential protective components in the whole grain that may be lost in the refining process. These include fermentable carbohydrates, phytochemicals, fiber, antioxidants and non-nutrients such as phenolic acids, lignans and phytoestrogens [1]. Components that are found in the outer layers of the whole grain are removed during the milling process. Researchers have focused on a number of these specific components without evaluating their effects
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