Letteratura scientifica selezionata sul tema "Aorta ring"
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Articoli di riviste sul tema "Aorta ring"
1
Stallone, J. N. "Role of endothelium in sexual dimorphism in vasopressin-induced contraction of rat aorta". American Journal of Physiology-Heart and Circulatory Physiology 265, n. 6 (1 dicembre 1993): H2073—H2080. http://dx.doi.org/10.1152/ajpheart.1993.265.6.h2073.
Testo completoAbstract (sommario):
In rat thoracic aorta, contractile responses to arginine vasopressin (AVP) are twofold higher in females than in males. To determine the role of the endothelium in this phenomenon, the effects of endothelium removal and inhibition of nitric oxide (NO) synthase and cyclooxygenase were examined in thoracic aortas prepared from male and female Sprague-Dawley rats and mounted for isometric tension recording. Maximal contractile response to AVP was substantially higher in female (4,232 +/- 316 mg/mg ring dry wt) than in male aortas (1,365 +/- 239; P < 0.01). Removal of the endothelium markedly potentiated maximal response to AVP in male aortas (4,100 +/- 422 mg/mg ring wt; P < 0.01); endothelium removal increased sensitivity but not maximal response in female aortas. Inhibition of NO synthase with NG-monomethyl-L-arginine (L-NMMA, 250 microM) doubled maximal contraction to AVP in male aortas (3,175 +/- 193 mg/mg ring wt; P < 0.01); L-NMMA increased sensitivity but not maximal response in female aortas. Inhibition of cyclooxygenase with indomethacin (10 microM) did not alter maximal response to AVP in male aortas but significantly attenuated responses of female aortas (2,816 +/- 306 mg/mg ring wt; P < 0.01). In contrast, maximal contractile response to phenylephrine hydrochloride (PE) was 40% higher in males than in females (P < 0.01); L-NMMA increased both the sensitivity and maximal response to PE to a greater extent in female (3,061 +/- 121 vs. 4,971 +/- 135 mg/mg ring wt; P < 0.01) than in male aortas (4,317 +/- 227 vs. 4,899 +/- 104 mg/mg ring wt; P < 0.01). (ABSTRACT TRUNCATED AT 250 WORDS)
2
Ozer, Erdem Kamil, Miyase Gozde Gunduz, Ahmed El-Khouly, Yildirim Sara, Rahime Simsek, Alper Bektas Iskit e Cihat Safak. "Synthesis of fused 1,4-dihydropyridines as potential calcium channel blockers". Turkish Journal of Biochemistry 43, n. 6 (12 giugno 2017): 578–86. http://dx.doi.org/10.1515/tjb-2016-0247.
Testo completoAbstract (sommario):
AbstractObjectiveThe aim of this study was to synthesize ten 1,4-dihydropyridine (DHP) derivatives in which substituted cyclohexane rings were fused to the DHP ring and to determine how different ester groups and the benzoyl substituent introduced in 4-phenyl ring affected their calcium channel blocking activity.MethodsA microwave-assisted one-pot method was applied for the synthesis of compound1–5according to a modified Hantzsch reaction. The benzoyl moiety was introduced in the 4-phenyl ring of these dihydropyridines by refluxing with benzoyl chloride in acetone in the presence of anhydrous potassium carbonate. Synthesized products were characterized by elemental analysis, IR,1H-NMR and13C-NMR spectroscopy. The inhibitory actions of compounds1–10on calcium channel blocking activity were tested on isolated rat aorta preparations.ResultsThe obtained pharmacological results showed that although all compounds are potent relaxing agents on isolated rat aorta smooth muscle, introduction of a benzoyloxy substitiuent on the phenyl ring (compound6–10) decreased the relaxant effect of these compunds.ConclusionThe reported 1,4-DHP derivatives have calcium channel blocking activity on rat aorta smooth muscle.
3
Mauchley, David C., Julia Massey Stiegler, Luz A. Padilla, Zviadi Aburjania, Robet Dabal e David Cleveland. "Repair of Rare Vascular Ring: Circumflex Aortic Arch with Associated Hypoplasia and Coarctation". World Journal for Pediatric and Congenital Heart Surgery 11, n. 2 (19 maggio 2019): 235–37. http://dx.doi.org/10.1177/2150135119828387.
Testo completoAbstract (sommario):
We describe a neonate with an unusual vascular ring formed by a right-sided aortic arch with associated coarctation and distal hypoplasia in the presence of an aberrant left subclavian artery. The descending aorta traveled behind the esophagus to descend on the left side of the spine. A left ductus arteriosus connected to the descending aorta completing the vascular ring, with notable esophageal compression. Surgical correction was accomplished through median sternotomy, resection of the hypoplastic circumflex arch, aortic arch advancement, and end-to-side anastomosis.
4
Stallone, J. N., J. T. Crofton e L. Share. "Sexual dimorphism in vasopressin-induced contraction of rat aorta". American Journal of Physiology-Heart and Circulatory Physiology 260, n. 2 (1 febbraio 1991): H453—H458. http://dx.doi.org/10.1152/ajpheart.1991.260.2.h453.
Testo completoAbstract (sommario):
Previously, we reported that, in the rat, pressor responsiveness to vasopressin (VP) is higher in males than in females during most phases of the estrous cycle. To explore the role of the vasculature in this phenomenon, we examined vascular reactivity to VP in thoracic aortas of male rats and female rats during each phase of the estrous cycle. Aortic rings were prepared from age-matched male and female Sprague-Dawley rats and mounted for isometric tension recording. Maximal response of female aortas to VP (4,246 +/- 163 mg/mg ring dry wt) was more than twice (P less than 0.001) that of male aortas (1,877 +/- 215 mg/mg ring wt). Sensitivity of female aortas to VP was substantially higher (P less than 0.001) than that of male aortas (EC50: 10.9 +/- 0.7 vs. 19.0 +/- 1.6 nM, respectively). Maximal rate of tension development (dT/dtmax) during contraction with VP was nearly twofold higher (P less than 0.01) in female aortas (536 +/- 23 mg/min) than in male aortas (300 +/- 19 mg/min). Maximal response, sensitivity, and dT/dtmax of female aortas did not vary significantly during the estrous cycle. Maximal response of female aortas to phenylephrine (PE; 1,251 +/- 93 mg/mg ring wt) was half that (P less than 0.001) of male aortas (2,546 +/- 194 mg/mg ring wt); sensitivity to PE did not differ significantly (EC50: 0.33 +/- 0.02 vs. 0.38 +/- 0.06 microM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
5
Chen, Jer-Shen, Chun-Yang Huang e Jih-Hsin Huang. "Vascular ring connector–related pseudoaneurysm of the descending aorta". Journal of Thoracic and Cardiovascular Surgery 148, n. 6 (dicembre 2014): 3236–37. http://dx.doi.org/10.1016/j.jtcvs.2014.02.019.
Testo completo
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Dydynski, Philip B., John S. Austin, Deborah Kozik e Bahaaldin Alsoufi. "Utility of Pre- and Postoperative Computed Tomography Angiography for the Evaluation of a Complex Vascular Ring". World Journal for Pediatric and Congenital Heart Surgery 10, n. 5 (settembre 2019): 654–56. http://dx.doi.org/10.1177/2150135119867586.
Testo completoAbstract (sommario):
We present the case of a neonate born with an unusual complex vascular ring formed by a left-sided aortic arch that had retroesophageal course to join a right-sided descending aorta and a very large right-sided arterial ductus from the right pulmonary artery to the descending aorta. Associated finings included aortic arch hypoplasia, aberrant right subclavian artery, and aberrant origin of the left pulmonary artery from the aorta. We focus on the role of computed tomography angiography in the preoperative and postoperative assessment of this complex anomaly.
7
Pockett, Charissa R., Reeni Soni e Andrew S. Mackie. "Innominate vein vascular ring provides novel insight into systemic venous embryogenesis". Cardiology in the Young 22, n. 4 (9 novembre 2011): 469–71. http://dx.doi.org/10.1017/s1047951111001879.
Testo completoAbstract (sommario):
AbstractAnomalies of the innominate vein are uncommon in congenital cardiac disease. We report a case of duplicate innominate veins forming a vascular ring encircling the ascending aorta. We postulate that this vascular ring represents the failure of both a dorsal and ventral precardinal anastomosis to regress.
8
Fulton, Clifford T., e John N. Stallone. "Sexual dimorphism in prostanoid-potentiated vascular contraction: roles of endothelium and ovarian steroids". American Journal of Physiology-Heart and Circulatory Physiology 283, n. 5 (1 novembre 2002): H2062—H2073. http://dx.doi.org/10.1152/ajpheart.00099.2002.
Testo completoAbstract (sommario):
The effects of constrictor prostanoid (CP) pathway inhibitors on vascular reactivity to vasopressin (VP) and phenylephrine (PE) were examined in thoracic aortas of male, female, and ovariectomized (OVX) female Sprague-Dawley rats. Maximal contractile response of control (Cont) aortas to VP was markedly higher in females (3,885 ± 332 mg/mg ring wt) than in males (810 ± 148 mg). Indomethacin (Indo; 10 μM) attenuated maximal response to VP in females (3,043 ± 277 mg) but not in males. SQ-29,548 (SQ; 1 μM) attenuated maximal response to VP in females (3,042 ± 290 mg) to a similar extent as Indo. Dazoxiben (Daz; 10 μM) alone had no effect, but Daz + SQ attenuated maximal contractile response to VP to a similar extent as SQ alone. Removal of the endothelium in female aortas attenuated contractile responses to VP in Cont aortas. OVX attenuated maximal contractile response to VP in Cont aortas (2,093 ± 329 mg) and abolished the attenuating effects of Indo. Indo, SQ, and Daz exerted identical effects on contractile responses of male, female, and OVX female aortas to PE. These findings establish the following in the rat aorta: 1) CP, probably thromboxane and/or endoperoxide, is responsible for ∼25–30% of contractile responses of females, but not males, to VP and PE; 2) CP production by the female aorta is primarily endothelial in origin; and 3) ovarian steroids modulate production and/or actions of CP in female aortas.
9
Bryant, Roosevelt, William Wallen, Raheel Rizwan e David L. Morales. "Modified Aortic Uncrossing Procedure: A Novel Approach for Norwood Palliation of Complex Univentricular Congenital Heart Disease With a Circumflex Aorta". World Journal for Pediatric and Congenital Heart Surgery 8, n. 4 (luglio 2017): 507–10. http://dx.doi.org/10.1177/2150135117712248.
Testo completoAbstract (sommario):
The circumflex aorta is a rare type of true vascular ring anomaly. It consists of a retroesophageal right aortic arch, a left-sided descending thoracic aorta, and a left-sided ligamentum arteriosum. The “aortic uncrossing procedure” described by Planché and Lacour-Gayet is the procedure of choice for managing this aortic anomaly in patients with a biventricular heart. The presence of a circumflex aorta in a patient with heterotaxy syndrome and univentricular congenital heart disease requiring Norwood palliation is highly unusual. We report such a case and describe our approach to its surgical management.
10
Matsumoto, Takeo, e Kozaburo Hayashi. "Stress and Strain Distribution in Hypertensive and Normotensive Rat Aorta Considering Residual Strain". Journal of Biomechanical Engineering 118, n. 1 (1 febbraio 1996): 62–73. http://dx.doi.org/10.1115/1.2795947.
Testo completoAbstract (sommario):
The effects of hypertension on the stress and strain distributions through the wall thickness were studied in the rat thoracic aorta. Goldblatt hypertension was induced by constricting the left renal artery for 8 weeks. Static pressure-diameter-axial force relations were determined on excised tubular segments. The segments were then sliced into thin ring specimens. Circumferential strain distributions were determined from the cross-sectional shape of the ring specimens observed before and after releasing residual stresses by radial cutting. Stress distributions were calculated using a logarithmic type of strain energy density function. The wall thickness at the systolic blood pressure, Psys, significantly correlated with Psys. The mean stress and strain developed by Psys in the circumferential direction were not significantly different between the hypertensive and control aortas, while those in the axial direction were significantly smaller in the hypertensive aorta than in the control. The opening angles of the stress-free ring specimens correlated well with Psys. The stress concentration factor in the circumferential direction was almost constant and independent of Psys, although the stress distributions were not uniform through the wall thickness. Histological observation showed that the wall thickening caused by hypertension is mainly due to the hypertrophy of the lamellar units of the media, especially in the subintimal layer where the stress increase developed by hypertension is larger than in the other layers. These results indicate that: (a) the aortic wall adapts itself to the mechanical field by changing not only the wall dimensions but also the residual stresses, (b) this adaptation is primarily related to the circumferential stress but not to the axial stress, and (c) the aortic smooth muscle cells seem to change their morphology in response to the mechanical stress.
Tesi sul tema "Aorta ring"
1
Faraa, Amer Ahmed Ghalb. "IN VITRO FUNCTIONAL INTERPLAY BETWEEN PERIVASCULAR ADIPOSE TISSUE AND FLAVONOIDS: CRITICAL ROLE OF BETA3 RECEPTOR AND SUPEROXIDE ANION". Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1206941.
Testo completoAbstract (sommario):
Flavonoids, a class of natural polyphenols abundantly present in our diet, have been shown to exert
in vitro vasorelaxant activity. This was ascribed to a direct effect on the smooth muscle or factors
released by the endothelium. Nowadays, perivascular adipose tissue (PVAT) is emerging as a fine
regulator of blood vessel contractility. Therefore, it is conceivable to hypothesize that flavonoids
vasoactivity may occur also through or is influenced, either positively or negatively, by PVATreleased factors. This hypothesis was assessed in vitro on rat aorta rings. Several flavonoids proved
to display both antispasmodic and spasmolytic activity towards noradrenaline-induced contraction
of rings deprived of PVAT (-PVAT). However, when PVAT was present (+PVAT), both activities
of some flavonoids were lost and/or much decreased. In rings-PVAT, the superoxide donor
pyrogallol mimicked the effect of PVAT, whereas in rings+PVAT the antioxidant mito-tempol
restored both activities of the two most powerful flavonoids, namely apigenin and chrysin. The
Rho-kinase inhibitor fasudil, or apigenin and chrysin concentration-dependently relaxed the vessel
active tone induced by the Rho-kinase activator NaF; the presence of PVAT counteracted apigenin
spasmolytic activity though only in the absence of mito-tempol. Similar results were obtained in
rings pre-contracted with phenylephrine. Finally, when β3 receptors were blocked by SR59230A,
the vasorelaxant activity of both flavonoids was no more affected by PVAT. These findings are
coherent with the hypothesis that both noradrenaline and apigenin activated adipocyte β3 receptors
with the ensuing release of mitochondrial superoxide anion, which once diffused toward myocytes
counteracted flavonoid vasorelaxant activity, thus underlining the control of adipocytes upon the
vascular tone. This phenomenon might limit the beneficial health effects of this class of natural
compounds in patients affected by either obesity and/or other pathological conditions characterized
by sympathetic nerve overactivity.
2
Ghalb, Faraa Amer Ahmed. "IN VITRO FUNCTIONAL INTERPLAY BETWEEN PERIVASCULAR ADIPOSE TISSUE AND FLAVONOIDS: CRITICAL ROLE OF BETA3 RECEPTOR AND SUPEROXIDE ANION". Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1207163.
Testo completoAbstract (sommario):
Flavonoids, a class of natural polyphenols abundantly present in our diet, have been shown to exert
in vitro vasorelaxant activity. This was ascribed to a direct effect on the smooth muscle or factors
released by the endothelium. Nowadays, perivascular adipose tissue (PVAT) is emerging as a fine
regulator of blood vessel contractility. Therefore, it is conceivable to hypothesize that flavonoids
vasoactivity may occur also through or is influenced, either positively or negatively, by PVATreleased factors. This hypothesis was assessed in vitro on rat aorta rings. Several flavonoids proved
to display both antispasmodic and spasmolytic activity towards noradrenaline-induced contraction
of rings deprived of PVAT (-PVAT). However, when PVAT was present (+PVAT), both activities
of some flavonoids were lost and/or much decreased. In rings-PVAT, the superoxide donor
pyrogallol mimicked the effect of PVAT, whereas in rings+PVAT the antioxidant mito-tempol
restored both activities of the two most powerful flavonoids, namely apigenin and chrysin. The
Rho-kinase inhibitor fasudil, or apigenin and chrysin concentration-dependently relaxed the vessel
active tone induced by the Rho-kinase activator NaF; the presence of PVAT counteracted apigenin
spasmolytic activity though only in the absence of mito-tempol. Similar results were obtained in
rings pre-contracted with phenylephrine. Finally, when β3 receptors were blocked by SR59230A,
the vasorelaxant activity of both flavonoids was no more affected by PVAT. These findings are
coherent with the hypothesis that both noradrenaline and apigenin activated adipocyte β3 receptors
with the ensuing release of mitochondrial superoxide anion, which once diffused toward myocytes
counteracted flavonoid vasorelaxant activity, thus underlining the control of adipocytes upon the
vascular tone. This phenomenon might limit the beneficial health effects of this class of natural
compounds in patients affected by either obesity and/or other pathological conditions characterized
by sympathetic nerve overactivity.
Libri sul tema "Aorta ring"
1
Archer, Nick, e Nicky Manning. Left-sided abnormalities. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198766520.003.0010.
Testo completoAbstract (sommario):
This chapter explores left-sided abnormalities, discussing venoatrial abnormalities (including partial anomalous pulmonary venous drainage, total anomalous pulmonary venous drainage, and left-sided SVC), atrioventricular abnormalities (mitral atresia and mitral hypoplasia), ventriculoarterial abnormalities (including aortic stenosis, aortic atresia, and hypoplastic le. heart syndrome), and arterial abnormalities (coarctation of the aorta, interrupted aortic arch, right aortic arch, aberrant subclavian artery, double aortic arch, persistent fifth aortic arch, vascular rings, and aorto-pulmonary window).
Capitoli di libri sul tema "Aorta ring"
1
Gänsslen, Axel, e Jan Lindahl. "Emergency Management: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA)". In Pelvic Ring Fractures, 179–89. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-54730-1_14.
Testo completo
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Backer, Carl L. "Vascular Rings". In Diseases of the Aorta, 97–109. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11322-3_7.
Testo completo
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St-Louis, Jean, Benoit Sicotte, Eric Breton e Ashok K. Srivastava. "Contractile effects of vanadate on aorta rings from virgin and pregnant rats". In Vanadium Compounds: Biochemical and Therapeutic Applications, 145–50. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4613-1251-2_18.
Testo completo
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Pluchinotta, Francesca R., e Vivek Muthurangu. "Congenital aortic disease". In The EACVI Textbook of Cardiovascular Magnetic Resonance, a cura di Massimo Lombardi, Sven Plein, Steffen Petersen, Chiara Bucciarelli-Ducci, Emanuela R. Valsangiacomo Buechel, Cristina Basso e Victor Ferrari, 531–37. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198779735.003.0053.
Testo completoAbstract (sommario):
Supravalvar aortic stenosis, aortic arch anomalies, and coarctation of the aorta are lesions involving the ascending and descending aortas, which can cause obstruction to left ventricular forward flow. In some cases, they can be associated with an anomalous borderline left ventricle. Obstructive lesions impose an increased afterload on the left ventricle and, if severe and untreated, result in hypertrophy and eventual dilatation and failure of the left ventricle. In addition, clinical manifestations of double aortic arches and other vascular rings include swallowing or respiratory symptoms due to extrinsic compression. In most cases, the anatomical diagnosis can be made from two-dimensional echocardiography. Common indications for performing cardiovascular magnetic resonance (CMR) are to refine an echocardiographic diagnosis before selecting a management plan or during follow-up to depict post-operative changes after surgical correction or catheter intervention. The goals of CMR in the assessment of patients with left-sided heart lesions are anatomical evaluation of the location, functional assessment of the haemodynamic burden, and identification of associated anomalies.
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Cummings, Kristopher W. "Abnormal Aorta and Aortic Branching". In Chest Imaging, 527–31. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780199858064.003.0091.
Testo completoAbstract (sommario):
Abnormal aorta and aortic branching discusses congenital variants of the aortic arch and great vessel branching. While many of these anomalies are incidental imaging findings in asymptomatic individuals, lesions such as a double aortic arch and right aortic arch with aberrant left subclavian artery produce vascular rings which can cause respiratory or esophageal symptoms. Certain anomalies such as a right aortic arch with mirror image branching are very frequently associated with other congenital cardiac abnormalities. Another common aortic congenital abnormality that may be diagnosed in early adulthood is aortic coarctation, frequently manifesting with upper extremity hypertension. As many of these lesions are first detected on chest radiography, the radiographic appearance and classification of these abnormalities is discussed in detail and supplemented by additional information that can be obtained with CT and MR.
6
Farne, Hugo, Edward Norris-Cervetto e James Warbrick-Smith. "Chest pain". In Oxford Cases in Medicine and Surgery. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780198716228.003.0015.
Testo completoAbstract (sommario):
A good way to come up with a list of causes is to visualize the anatomy of the affected area and think of what could go wrong. Thus, in chest pain, there may be pathology of the heart, aorta, lungs, pulmonary vessels, oesophagus, stomach, thoracic nerves, thoracic muscles, or ribs. The main causes of acute chest pain in an individual aged over 60 include are listed in Figure 9.1. A younger patient is less likely to be suffering from diseases of old age, such as: • Acute coronary syndrome • Stable angina • Myopericarditis (usually post-infarction) • Thoracic aortic dissection • Thoracic aortic aneurysm A younger female patient on the combined oral contraceptive pill is more likely to be suffering from: • PE (the combined oral contraceptive pill is thrombogenic) • Pneumothorax (especially if tall and thin) • Cocaine-induced coronary spasm (still rare, but particularly unusual in older people). The following diagnoses require immediate management and should be kept in mind: • Acute coronary syndrome (unstable angina, or myocardial infarction (MI)) • Aortic dissection • Pneumothorax • PE • Boerhaave’s perforation The key features of each are listed below. 1 Features of acute coronary syndrome ■ History of sudden-onset, central, crushing chest pain radiating to either/both arms, neck or jaw, usually lasting a few minutes to half an hour (longer if there is ongoing infarction). Have a higher index of suspicion in those with a previous history of angina on exertion or MI and/or cardiovascular risk factors (smoking, hypertension, hypercholesterolaemia, diabetes mellitus, family history). ■ Signs of hypercholesterolaemia: cholesterol deposits in small skin lumps on the back of the hand or bony prominences like elbows (xanthomata), in creamy spots around the eyelids (xanthelasma), or a creamy ring around the cornea (arcus). Note that arcus is a normal finding in older people. ■ Signs of peripheral (atherosclerotic) vascular disease: weak pulses, peripheral cyanosis, cool peripheries, atrophic skin, ulcers, bruits on auscultation of carotids. ■ Signs of brady- or tachyarrhythmia. An arrhythmia is relevant for two reasons.
7
Taber, Douglass F. "The Carreira Synthesis of (+)-Daphmanidin E". In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0092.
Testo completoAbstract (sommario):
(+)-Daphmanidin E 3, isolated from the leaves of Daphniphyllum teijsmanni, shows moderate vasorelaxant activity on the rat aorta. Considering the curiously compact structure of 3, Erick M. Carreira of ETH Zürich chose (Angew. Chem. Int. Ed. 2011, 50, 11501) to start the synthesis from the enantiomerically pure bicyclic diketone 2. The mono enolate of 2 was readily prepared, but the steric bulk of the ketal of 4 was needed to direct the subsequent hydroboration. Indeed, the alkene of 5 was so congested that excess BH3 at elevated temperature was required. Under those conditions, the esters were also partially reduced, so the reduction was completed with Dibal to deliver the crystalline triol 6. After protection of the alcohols, the remaining carbon atoms of 3 were added by sequential Claisen rearrangements. O-Alkylation with 7 delivered 8, which rearranged with 10:1 diastereoselectivity. After O-allylation, the second Claisen rearrangement led to 9 as the only isolable product. Selective hydroboration of 9 led to 10, which was deprotected, then dehydrated following the Grieco protocol. Functional group manipulation of 11 led to the aldehyde 12, which was condensed with nitromethane to give 13. Direct conjugate addition to 13 gave at best a 1:3 preference for the wrong diastereomer. With a chiral Cu catalyst, this was improved to 5:1 in favor of the desired diastereomer. Ozonolysis of 14 followed by selective reduction of the aldehyde gave the primary alcohol, which was carried onto the iodide. Elimination with DBU then delivered 15, setting the stage for the key intramolecular bond connection. After extensive exploration, it was found that irradiation of 15 in the presence of a catalytic amount of a cobaloxime catalyst and a stoichiometric amount of Hünig’s base gave clean cyclization to 16. The last carbocyclic ring of (+)-daphmanidin E 3 was closed by intramolecular aldol addition of the aldehyde of 17 to the ketone, followed by dehydration. The seemingly simple intramolecular imine formation to prepare the natural product, initially elusive, was effected by heating the ammonium salt in ethanol. The Co-catalyzed cyclization of 15 to 16 is particularly striking.
8
Morrison, Louise, e Brian A. McCrossan. "Cardiac evaluation of a child with stridor". In Challenging Concepts in Congenital and Acquired Heart Disease in the Young, 237–46. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198759447.003.0018.
Testo completoAbstract (sommario):
This is the case of a 6-month-old boy who is diagnosed with, and treated for, a vascular ring, following several admissions to paediatric intensive care with difficult respiratory symptoms and ongoing failure to thrive. This case highlights the diagnostic challenge presented by these patients. Cardiovascular causes of paediatric airway compression are often under-recognized, with consequent delay in diagnosis. Although they are much less common than other causes of stridor, such as laryngomalacia or other tracheo-bronchial anomalies, chronic airway compression in childhood from vascular malformations carries significant morbidity and mortality. It is readily treatable and should not be overlooked. A high index of suspicion for mechanical compression should be maintained in small children with recurrent obstructive respiratory signs and symptoms or the older child presenting with dysphagia. The most prevalent vascular anomalies resulting in airway compression are a double aortic arch, right aortic arch with an aberrant left subclavian artery, innominate artery compression, left aortic arch with an aberrant right subclavian artery (rarely), and pulmonary artery sling. Rarely, complex congenital heart disease, itself leading to dilatation of the cardiac structures, may precipitate airway compromise, as in tetralogy of Fallot with an absent pulmonary valve syndrome or conditions with significant atrioventricular valve regurgitation causing left atrial enlargement. A dilated ascending aorta may compress the trachea, producing similar symptoms likewise with a cervical aortic arch with an aberrant sublclavian artery and ipsilateral ligamentum arteriosus. Such cases require a comprehensive diagnostic workup. Investigations include plain chest X-ray, echocardiogram, direct microlaryngoscopy and bronchoscopy, and CT angiography or cardiac MRI. A normal laryngoscopic examination should warrant further investigation in the presence of ongoing symptoms. An appreciation of aortic arch embryology is important in interpreting echocardiography and cross-sectional imaging in relation to the role of airway compression. Management often necessitates multidisciplinary collaboration among specialties, including ear, nose, and throat (ENT) specialists, paediatric cardiologists, respiratory physicians, intensivists, and cardiothoracic surgeons. Definitive treatment depends on the underlying pathology but usually involves surgical decompression or aortopexy. A proportion of patients will continue to exhibit symptoms following surgical release, due to ongoing weakness of the airway, and in severe cases may require ongoing respiratory support.
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Emani, Sitaram M. "Patent Ductus Arteriosus, Coarctation of the Aorta, and Vascular Rings". In Sabiston and Spencer's Surgery of the Chest, 1781–95. Elsevier, 2010. http://dx.doi.org/10.1016/b978-1-4160-5225-8.00113-6.
Testo completo
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K. Day, Thomas. "Role of Arterial Pressure, Wall Stiffness, Pulse Pressure and Waveform in Arterial Wall Stress/Strain and Its Clinical Implications". In Risk Factors for Cardiovascular Disease. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.100048.
Testo completoAbstract (sommario):
Biomechanical stress applied to the intima of arteries has long been suspected as a factor in the initiation and localisation of atherosclerotic plaque, and it is implicated in the separation of plaque from the underlying arterial wall giving rise to the acute clinical consequences of thrombosis, dissection and embolism. The factors underlying transmural stress were investigated in-vitro using fresh porcine abdominal aortas on an experimental rig in which pulse pressure, pulse waveform, fluid viscosity, pulse rate, vessel wall compliance and systolic and diastolic blood pressure could be varied at will. Vessel wall compliance was progressively reduced by exposure of the artery to formaldehyde vapour for increased periods of time, a saline-treated artery being used as control. Centripetal transmural stress (CTS) and strain were studied by direct observation of the displacement of a compliant false intima (FI) using real-time B and M mode ultrasound, and by measuring the differential pressure between the space beneath the FI and the adjacent vessel lumen. CTS was found to be directly related to pulse pressure (r = 0.907, p < 0.001) and inversely related to vessel wall compliance. It was independently affected by ranked peak pressure waveform (R = 0.93, p < 0.01) being higher with sharp peak pressure and lower when the waveform was rounded, and it peaked in early diastole in untreated vessels, and both in diastole and peak systole in ones stiffened by formaldehyde vapour. Mean arterial pressure exerted a profound effect via its effect on vessel wall stiffness, which was found to rise 7-fold across the mean arterial pressure range 50-130 mmHg and continued to increase in a logarithmic fashion as the upper physiological range of mean arterial pressure was exceeded. There are two potential clinical implications: in mitigating the postulated biomechanical aspects atherogenesis and atherosclerotic plaque detachment, maintaining large vessel wall compliance is important, and the main factor determining this in a healthy artery is mean arterial pressure; if the arterial wall has already become stiffened as a result of disease, and in the absence of critical stenosis, the findings suggest that the appropriate therapeutic targets are modification of pulse pressure and pulse waveform profile. Simply reducing the diastolic pressure in elderly patients may be unwise if the result is a widened pulse pressure and increased transmural strain. The distribution of atheroma at points of focal mechanical strain in the vessel wall may be explicable if the stress induced by an excessive pulse pressure provokes the inflammatory changes seen in repetitive strain injury. Investigation of inflammatory signalling in the vessel wall provoked by repeated mechanical stress may represent a productive area for future research.
Atti di convegni sul tema "Aorta ring"
1
Bult, H., F. Jordaens, A. G. Herman, C. Van Hove e T. J. Verbeuren. "RELEASE OF ENDOTHELIUM DERIVED RELAXING FACTOR (EDRF), PROSTACYCLIN (PGI2) AND ANTI-PLATELET ACTIVITY BY RABBIT AORTIC ENDOTHELIUM". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643797.
Testo completoAbstract (sommario):
Endothelium may release EDRF and PGI2; the former causes relaxation of arterial smooth muscle cells, whereas PGI2 suppresses phagocyte and platelet activation and may relax some arteries. The aim of the present experiments was to investigate whether EDRF from rabbit aorta affects platelet reactivity. To this end the isolated thoracic aorta was perfused with a Krebs' solution (3 ml/min), andthe perfusate was continuously super fused over a de-endothe-lialized ring of the abdominal aorta, contracted withnoradrenaline in the presence of atropine, to monitor EDRF. Aliquots (200 μl) ofeffluent were also added to 200 (il prewarmedautologous citrate platelet rich plasma, which was immediately stimulated with ADP or U46619, a thromboxane (TX) A2 mimetic. Both agonists induce aggregation independently of TXA2 formation. Finally, the PGI2 content of the effluent was assessed by specific radioimmunoassay of 6-oxo-PGF1alpha(ir-6oxo). Infusion of 0.3,1 and 3 μM acetylcholine (Ach) through the aorta for 7.5 min caused a dose-dependent relaxation of the abdominal ring (33 to 100 % at 3 (μM Ach), indicating intraluminal EDRF release. Maximum relaxation was reached in 3 min and maintained. Release of platelet inhibitory activity was variable. At 3 μM Ach, anti-platelet activity(more than 10 % suppression of aggregation)was present in the effluent of 5 (of 7) aorta's for ADP-, and in effluent of 6 (of 7) aorta's for U46617-induced aggregation. U46619 was more sensitive to the anti-platelet activity, a finding consistent withauthentic PGI2. When a clear anti-platelet activity was monitored, its release was abolished by indo-methacin, which affected neither EDRF release nor platelet aggregation. Baseline release of ir-6oxo was low and variable, but dose-dependently stimulated by Ach, reaching a maximum for each concentration in the 2nd to 3rd minute. In contrast to EDRF, ir-6oxo release was not maintained during the subsequent 4 min and tapered off. Formation of ir-6oxo and anti-aggregatingeffect were positively correlated, but therewas no association between EDRF and ir-6oxo or anti-platelet activity. In conclusion, rabbit aortic endothelium could release EDRF and PGI2, but the present set-up did not reveal an anti-platelet effect of EDRF.
2
Tamura, Atsutaka, e Koki Matsumoto. "Regional and Layer Distribution of Residual Stresses in an Unloaded Aortic Medial Wall". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23632.
Testo completoAbstract (sommario):
Abstract The mechanical and structural characteristics of aortic media have profound effects on the physiology and pathophysiology of an aorta. However, many aspects of the aortic tissue remain poorly understood, partly due to the intrinsic layered wall structure and regionally varying residual stresses. Our recent works have demonstrated that a mechanical interaction between the elastic lamina (EL) and smooth muscle layer in the aortic media can be computationally reproduced using a simplified finite element (FE) model. However, it is questionable whether the simplified FE model we created was representative of the structure of a real medial wall and its modeling technique would be applicable to develop a more sophisticated and structure-based aortic FE model. This study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state and successfully reproduced transmural variation in EL waviness across the aortic wall. We also aimed at confirming the inner and outer layers of the medial wall are subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. Moreover, the computed residual stresses were found to be within the reasonable range of the predicted values, 1–10 kPa, supporting the validity of our modeling approach. Although further study is required, the information obtained here will greatly help improve the understanding of basic aortic physiology and pathophysiology, while simultaneously providing a basis for more sophisticated computational modeling of the aorta.
3
Moreno, A., J. P. de la Cruz, J. Garcia Campos e F. Sanchez de la Cuesta. "EFFECT OF DIPYRIDAMOLE + ASA ON THE RETINE VASCULAR PATTERN OF ESTREPTOZOTOCIN-DIABETIC RATS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643098.
Testo completoAbstract (sommario):
INTRODUCTIONWe have used an experimental model which allows the evaluation of the qualitative differences in the retinal vascular pattern by means of the labeling of the retine vascular tree with radish peroxidase (HRP) in estreptozotocin-diabetic rats. The aim of the study was to evaluate the effect of ASA and DIP + ASA on the vessels platelet behaviour of said retine pattern in a group of rats in t-hich the diabetes had 3 months of evolution.PROCEDURE22 Wistar male rats were divided into A groups; 1) control group, 2) diabetic rats without antiaggregant, 3) dietetic rats treated with 6 mg/day ASA p.o., 4) diabetic rats treated with 6 mg/day ASA +12 mg/day DIP p.o. For inducing diabetes 30 mg/Kg of i.v. estreptozotocine were administered. The animals were considered “diabetic” when glucemia was over 200 mg/100 ml. After 3 months of treatment with 4IU insuline and ASA, or ASA + DIP, the animals were sacrified. Samples of blood and rings of descending aorta were extracted. Platelet aggregation in IJB in front of 1 μg/ml of collagen and the prostacycline-like activity of the aorta ring were evaluated. The configuration of the retine vascular tree labeled with HRP was observed.RESULTS AND CONCLUSIONSMaximal aggregation intensity: 11.1 Ω in the control group,10.9Ω in the diabetic non-treated group, 4.8Ω in rats receiving ASA and 4.6Ω in rats treated with DIP + ASA. The incUbation during 10 min. of aorta rings in blood samples produced 38.7% inhibition in the control group, 12.8% in the non treated-diabetic group 0% in the ASA group and 49.3% in the group treated with DIP + ASA.The qualitative changes in the diabetic rats retinal vascular network non treated with antiaggregants showed a scarce visibility of capillars as well as large zones of tortuous vessels. The rats treated with ASA showed a continuous vascular bed and less tortuous vessels than the ones in the non treated group but the vascular diameters were smaller than the ones observed in non-diabetic rats; the rats treated with DIP + ASA showed a continuous vascular bed, scarce tortuous vessels and vascular diameters similar to the ones found in non-diabetic rats. Mortality rates: 0% in the control group, 50% in the non-treated diabetic group, 16% in the ASA group and 0% in the DIP + ASA group. The administration of DIP + ASA normalized the prostacycline-like activity and the retinal vascular pattern in estreptozotocin-diabetic rats.
4
Yamada, Hiroshi, Kousuke Yasuno, Kensuke Fujisaki e Hiroshi Ishiguro. "Hardening of the Porcine Thoracic Aorta Subjected to Freezing and Thawing: Experimental Evaluation and Mathematical Modeling". In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52339.
Testo completoAbstract (sommario):
Identifying changes in the mechanical behavior of blood vessels subjected to freezing and thawing, such as occur with cryopreservation, are of key importance. Excising pairs of fresh ring specimens from identical porcine thoracic aortas (n = 8 for each cooling rate), we carried out uniaxial tensile loading and unloading tests over the physiological stress range (first and second tests) and performed a loading test until the breaking point within the range of a load cell (third test). After the first test, one specimen of the pair was frozen at −80°C at a cooling rate of −1°C or −50°C/min and thawed, while the other was held at 5°C as a control. At both cooling rates, for the specimens subjected to freezing, the ratios of the tangential modulus in the stress-strain curve (between 130 and 150 kPa) in the second test to that in the first test differed significantly (p < 0.01) from the respective ratios of the control specimens. We formulated a mathematical model of the stress–strain relationship considering elastic and collagen fibers and an incompressible fluid phase. We evaluated the working hypothesis that collagen fibers reduce their extensibility either by hardening as a mechanical change or by shortening as a geometric change. We attributed this response to the formation of dehydration-induced cross-linking in collagen molecules at the microscopic level.
5
Haghighipour, Nooshin, Mohammad Tafazzoli Shadpour e Albert Avolio. "Residual Stress and Circumferential Stress Distribution in a Finite Element Model of the Arterial Wall". In ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58313.
Testo completoAbstract (sommario):
Stress distribution of the arterial wall is an important factor in biomechanics of arteries. It has been suggested that excessive stress leads to arterial degeneration and lesion formation. In addition to circumferential tensile stress caused by luminal pressure, arterial wall contains circumferential residual stress with compressive and tensile components with maximum values on intima and adventitia respectively. The compressive residual stress component compensates part of maximum tensile stress, and therefore decreases severity of tension on endothelial lining. If an arterial ring is cut in radial direction it opens. The degree of opening angle is a determinant of circumferential residual stress. In this investigation, Finite element modeling was used to evaluate circumferential residual stress in a typical model of cross section of human aorta with differing opening angle and Young’s modulus of elasticity. Results show that residual stress values are influenced by structural and mechanical parameters. Elevation of the opening angle and stiffening of the arterial wall resulted in increase of residual stress level.
6
Azeloglu, Evren U., Michael B. Albro, Vikrum A. Thimmappa, Charles R. Haggart, Kenneth W. Ng, Gerard A. Ateshian e Kevin D. Costa. "The Role of Proteoglycans on Residual Stresses in the Aorta". In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176566.
Testo completoAbstract (sommario):
Arteries exhibit significant residual stresses, most notably demonstrated by the tendency of rings of arterial wall to open when cut radially [1, 2]. Residual stresses play an important role in the identification of appropriate reference configurations, and hence the definition of stresses and strains in the tissue; they are also important in vascular growth, remodeling and disease [3–5]. Though it has been suggested that elastin appears to be primarily responsible for residual stresses in arteries [6], no explicit mechanism has been described to date which can explain how these residual stresses might be induced, and why they might vary along the length of arteries such as the aorta.
7
Colombo, Giorgio, Simone Bartesaghi e Eduardo Pallares. "A Method to Design Custom-Fit Stent Graft for Abdominal Aortic Aneurism". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52078.
Testo completoAbstract (sommario):
Abdominal Aorta Aneurysm (AAA) affects aorta, especially above the iliac bifurcation where the Wall Shear Stress (WSS) is greater. Consequence may be fatal in case of breakage; a way to treat it is Endovascular Aneurysm Repair (EVAR) where a stent graft is placed inside the aorta without open surgery requirement. Because of the standards, stent graft can be chosen between several sizes: in some cases, this device cannot fit perfectly with the anatomy of the patient and this can lead to a not optimal behavior of the prosthesis and further complications. This study present a method to design and test specific custom-fit stent graft able to better adapt to the patient artery improving the efficiency of the prosthesis and reducing the risk of the migration of the graft as well as the fabric torn. The design method is based on a 3D geometric model of the aorta, generated from CT scan data. Centrelines and geometric data for cross sections along the aorta are the inputs necessary to define the mesh of the stent. A custom algorithm is developed to size the stent in relation to the geometric data of the specific patient; when the frame of the prosthesis is defined, a CAD-based Loft Surface has used to define surfaces between the stent rings. For the bifurcation, again CAD-based Boundary Surfaces is used. The described procedure has been also applied in a Augmented Virtual Reality simulation of the EVAR and, finally, it permits a CFD simulation to evaluate the behavior of the prosthesis inserted into the aorta.
8
Kratzberg, Jarin, Patricia Walker, Elizabeth Rikkers e Madhavan Raghavan. "The Effect of Proteolytic Enzymatic Treatment on Plastic Deformation of Porcine Aortic Tissue". In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60038.
Testo completoAbstract (sommario):
We investigated the feasibility of developing an in vitro abdominal aortic aneurysm model by mechanically stretching passive porcine aortic tissue after enzymatic degradation of its structural proteins. Individual arterial rings, taken from the thoracic and abdominal porcine aorta were exposed to specific concentrations of collagenase (to degrade collagen) and/or elastase (to degrade elastin). The specimens were then cut into flat strips and subjected to uniaxial incremental creep tests of increasing load amplitude. The plastic strain (strain at zero load) after each creep load cycle was recorded until specimen failure. The maximum plastic strain due to enzymatic degradation and mechanical loading in elastase treated specimens (mean+SD = 45.1±14.7%; p<0.001) was significantly higher than in untreated controls (19.4±7.61%). However, the plastic strain in collagenase treated specimens (18.4±10.3%; p = 0.79) was not significantly different from the controls. Because AAA is associated with a plastic deformation of 200–400%, the results suggest that it is not feasible to develop an in vitro AAA model by enzymatic degradation and biomechanical stretching of passive porcine aorta. Consequently, these findings suggest that aneurysm growth is unlikely to be solely the result of pressure induced passive stretch of a weakened aorta.
9
Katušić, Z. S., e M. K. Krstić. "ENDOTHELIUM-INDEPENDENT PARTIAL AGONISTIC ACTIVITY OF VASOPRESSIN IN THE RAT COMMON CAROTID ARTERY". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644600.
Testo completoAbstract (sommario):
It has been shown that vasopressin causes endothelium-dependent relaxations of the canine basilar artery, suggesting that_increased circulating concentrations of vasopressin can produce redistribution of the blood from the peripheral to the cerebral circulation (Katušić et al., 1984). The present experiments were done to examine effect of vasopressin on the rat peripheral arteries* The experiments were performed on rings (4 mm long) of aorta, common carotid and renal arteries* The arteries were placed in Krebs-Ringer-bicarbonate solution gassed with 95%O2-5%co2 gas mixture and kept at 37°c. In certain rings the endothelium was removed mechanically by gentle rubbing of the intimal surface. Isometric tension was continously recorded (IPM electronic).Vasopressin (10-11 to 3×10-8 M) caused concentration-dependent contraction being full agonist in aorta and renal artery, but partial agonist in common carotid artery. After removal of endothelium vasopressin-induced contractions were not significantlly afected in any of the tested arteries. Gyclooxygenase inhibitor indomethacin (10-5 M; contact time = 40 min) did not affect partial agonistic activity of vasopressin in common carotid artery. This results indicate that partial agonistic activity of vasopressin in common carotid artery is not related to increased production of "EDRF" or prostacyclin from endothelium. In addition, our findings are consistent with the hypothesis that vasopressin may contribute to redistribution of the blood flow from the peripheral to the cerbral circulation.Z.S. Katušić, J.T. Shepherd and P.M. Vanhoutte. Circ. Res., 55: 575-579, 1984
10
fu, Xihong, KANG SHIFA, JIA XIN, LI SHUO, CAO mingqiang, JI bindong, ZHAO yue e SHI yuanyuan. "Research on the quantitative process technology of tightening torque of optical lens pressure ring". In Advanced Optical Manufacturing Technologies and Applications 2022; and 2nd International Forum of Young Scientists on Advanced Optical Manufacturing (AOMTA and YSAOM 2022), a cura di Xuejun Zhang, Lingbao Kong, Dawei Zhang, Changxi Xue, Yuegang Fu, Donglin Xue e Hongbo Sun. SPIE, 2023. http://dx.doi.org/10.1117/12.2655687.
Testo completo