Iliac-hepatic arterial bypass for compromised collateral flow during modified Appleby operation for advanced pancreatic cancer

Involvement of the celiac trunk and common hepatic artery are two of the most common forms of vascular invasion by tumours of the distal pancreas, and until recently this finding was considered a contra-indication to resection. We described a modified Appleby operation for locally advanced distal pancreatic cancer with compromised hepatic collateral flow that needed hepatic arterial revascularization, successfully accomplished by left external iliac-hepatic arterial bypass with Dacron prosthesis. Patient recovery was uneventful and he was discharged on the 10th postoperative day. Postoperative angio-CT disclosed a patent arterial bypass. Patient is well and asymptomatic 13 months after operation. At the time of this writing, postoperative CT scan showed no evidence of disease and CA 19-9 level is normal. There is a well established rationale to perform extended resection of pancreatic carcinomas that compromise vascular structures. Modified Appleby procedure can safely be performed, has oncological advantages to palliative procedures and provides relief of pain but is reserved for selected patients. Preservation of hepatic arterial flow has utmost importance to avoid hepatobiliary complications as liver necrosis, liver abscess, gallbladder necrosis or cholecystitis. In this case, hepatic revascularization was particularly challenging, but was successfully accomplished by left external iliac-hepatic arterial bypass. To our knowledge this type of arterial bypass has never been described so far in the English literature and its description may be important for surgeons dealing with advanced pancreatic cancer. (C) 2009 Elsevier Ltd. All rights reserved.

Collateral, default penalties and infinite horizon equilibrium

Pascoa and Seghir (2009) noticed that when collateralized promises become subject to utility penalties on default, Ponzi schemes may occur. However, equilibrium exists in some interesting cases. Under low penalties, equilibrium exists if the collateral does not yield utility (for example, when it is a productive asset or a security). Equilibrium exists also under more severe penalties and collateral utility gains, when the promise or the collateral are nominal assets and the margin requirements are endogenous: relative inflation rates and margin coefficients can make the income effects dominate the penalty effects. An equilibrium refinement avoids no-trade equilibria with unduly repayment beliefs. Our refinement differs from the one used by Dubey, Geanakoplos and Shubik (2005) as it does not eliminate no trade equilibria whose low delivery rates are consistent with the propensity to default of agents that are on the verge of selling.

A Model of Collateral, Investment, and Adverse Selection

This paper characterizes the relationship between entrepreneurial wealth and aggregate investment under adverse selection. Its main finding is that such a relationship need not be monotonic. In particular, three results emerge from the analysis: (i) pooling equilibria, in which investment is independent of entrepreneurial wealth, are more likely to arise when entrepreneurial wealth is relatively low; (ii) separating equilibria, in which investment is increasing in entrepreneurial wealth, are most likely to arise when entrepreneurial wealth is relatively high and; (iii) for a given interest rate, an increase in entrepreneurial wealth may generate a discontinuous fall in investment.

Bubbly collateral and economic activity

This paper develops a model of the bubbly economy and uses it to study the effects of bailoutpolicies. In the bubbly economy, weak enforcement institutions do not allow firms to pledge futurerevenues to their creditors. As a result, "fundamental" collateral is scarce and this impairs the intermediationprocess that transforms savings into capital. To overcome this shortage of "fundamental"collateral, the bubbly economy creates "bubbly" collateral. This additional collateral supports anintricate array of intra- and inter-generational transfers that allow savings to be transformed intocapital and bubbles. Swings in investor sentiment lead to fluctuations in the amount of bubblycollateral, giving rise to bubbly business cycles with very rich and complex dynamics.Bailout policies can affect these dynamics in a variety of ways. Expected bailouts provideadditional collateral and expand investment and the capital stock. Realized bailouts reduce thesupply of funds and contract investment and the capital stock. Thus, bailout policies tend to fosterinvestment and growth in normal times, but to depress investment and growth during crisis periods.We show how to design bailout policies that maximize various policy objectives.

A model of collateral, investment and adverse selection

This paper characterizes the relationship between entrepreneurial wealth and aggregate investmentunder adverse selection. Its main finding is that such a relationship need not bemonotonic. In particular, three results emerge from the analysis: (i) pooling equilibria, in whichinvestment is independent of entrepreneurial wealth, are more likely to arise when entrepreneurialwealth is relatively low; (ii) separating equilibria, in which investment is increasing inentrepreneurial wealth, are most likely to arise when entrepreneurial wealth is relatively highand; (iii) for a given interest rate, an increase in entrepreneurial wealth may generate a discontinuousfall in investment.

Endovascular abdominal aneurysm repair and impact of systematic preoperative embolization of collateral arteries: endoleak analysis and long-term follow-up.

PURPOSE: To report our results of endovascular aneurysm repair (EVAR) over a 10-year period using systematic preoperative collateral artery embolization. METHODS: From 1999 until 2009, 124 patients (117 men; mean age 70.8 years) with abdominal aortic aneurysm (AAA) underwent embolization of patent lumbar and/or inferior mesenteric arteries prior to elective EVAR procedures. Embolization was systematically attempted and, whenever possible, performed using microcoils and a coaxial technique. Follow-up included computed tomography and/or magnetic resonance imaging and abdominal radiography. RESULTS: The technical success for EVAR was 96% (119/124), with 4 patients dying within 30 days (3.2% perioperative mortality) and 1 type III endoleak accounting for the failures. Collateral arteries were occluded spontaneously or by embolization in 60 (48%) of 124 patients. The endoleak rate was 50.9% (74 in 61 patients), most of which were type II (19%). Over a mean clinical follow-up of 60.5±34.1 months (range 1-144), aneurysm sac dimensions decreased in 66 patients, increased in 19 patients, and were stable in 35. The endoleak rate was significantly higher in the patients with increasing sac diameter (p<0.001). Among the patients with patent collateral arteries, 38/64 (59.3%) developed 46 leaks, while 28 leaks appeared in 23 (41%) of 56 patients with collateral artery occlusion (p=0.069). The type II endoleak rate significantly differed between these two groups (47.8% vs. 3.6%, p<0.001). CONCLUSION: Preoperative collateral embolization seems to be a valid method of reducing the incidence of type II endoleak, improving the long-term outcome.

Recovery of paraplegia after type B dissection due to spinal collateral recruitment.

Acute paraplegia could be a symptom of aortic dissection due to sudden compromise of arterial spinal cord blood supply. Complete spontaneous neurologic recovery is possible and was observed in the present case 3 hours after symptom onset. Spontaneous spinal cord reperfusion after acute type B dissection was probably due to two main mechanisms. Reperfusion of false lumen and collateral vascular network recruitment, recently confirmed by anatomic animal studies, serve as potential explanations. Favorable evolution of acute paraplegia after aortic dissection exists, but prognosis is uncertain, probably due to individual variable anatomic distribution of spinal cord blood supply.

The extent of the collateral circulation influences the postprandial increase in portal pressure in patients with cirrhosis.

Background: In cirrhosis, repeated flares of portal pressure and collateral blood flow provoked by postprandial hyperaemia may contribute to variceal dilation and rupture. Aim: To examine the effect of the extent of the collateral circulation on the postprandial increase in portal pressure observed in cirrhosis. Patients and methods: The hepatic venous pressure gradient (HVPG), hepatic blood flow and azygos blood flow were measured in 64 patients with cirrhosis before and after a standard liquid meal. Results: Peak increases in HVPG (median+14.9%), hepatic blood flow (median+25.4%), and azygos blood flow (median+32.2%) occurred at 30 min after the meal. Compared with patients with marked postprandial increase in HVPG (above the median, n¿=¿32), those showing mild (<15%, n¿=¿32) increase in HVPG had a higher baseline azygos flow (p<0.01) and underwent a greater postprandial increase in azygos flow (p<0.02). Hepatic blood flow increased similarly in both groups. Postprandial increases in HVPG were inversely correlated (p<0.001) with both baseline azygos flow (r¿=¿¿0.69) and its postprandial increase (r¿=¿¿0.72). Food intake increased nitric oxide products in the azygos (p<0.01), but not in the hepatic vein. Large varices (p<0.01) and previous variceal bleeding (p<0.001) were more frequent in patients with mild increase in HVPG. Conclusions: Postprandial hyperaemia simultaneously increases HVPG and collateral flow. The extent of the collateral circulation determines the HVPG response to food intake. Patients with extensive collateralisation show less pronounced postprandial increases in HVPG, but associated with marked flares in collateral flow. Collateral vessels preserve their ability to dilate in response to increased blood flow.

On regeneration and collateral sprouting to hind limb digits after sciatic nerve injury in the rat

This study examines the proportions of regenerative and collateral sprouting to the skin after peripheral nerve injury. Methods: In the first experimental paradigm, primary afferent neurones were pre-labelled with Diamidino Yellow (DY), injected in digit 3, followed by sciatic nerve section and repair. After three months of regeneration, digit 3 was re-injected with Fast Blue (FB) to label regernating cells. Fluoro-Gold (FG) was applied to the femoral (FEM) and musculocutaneous (MC) nervers four days later to quantify their contribution to the innveration. In the second experimental paradigm, sciatic nerve was first sectioned and repaired. Three months later, the sciatic was resected, and digit 3 injected with FB. After four more days, FEM and MC were resected and FG injected in all digits. Results: Neurones in dorsal root ganglion (DRG) L5 had a higher rate of correct reinnervation of digit 3 (44-72%) than neurones in DRG L4 (14-44%). Like in control cases, only occasional axons were traced from the FEM and MC. In the second experiment, only occasional labelled neurones appeared. Conclusions: The results indicate differences in the capacity for correct peripheral sensory reinnvervation between segmental levels and that in this model collateral sprouting was practically non-existent compared to regenerative sprouting.

Collateral methotrexate resistance in cisplatin-selected murine leukemia cells

Resistance to anticancer drugs is a major cause of failure of many therapeutic protocols. A variety of mechanisms have been proposed to explain this phenomenon. The exact mechanism depends upon the drug of interest as well as the tumor type treated. While studying a cell line selected for its resistance to cisplatin we noted that the cells expressed a >25,000-fold collateral resistance to methotrexate. Given the magnitude of this resistance we elected to investigate this intriguing collateral resistance. From a series of investigations we have identified an alteration in a membrane protein of the resistant cell as compared to the sensitive cells that could be the primary mechanism of resistance. Our studies reviewed here indicate decreased tyrosine phosphorylation of a protein (molecular mass = 66) in the resistant cells, which results in little or no transfer of methotrexate from the medium into the cell. Since this is a relatively novel function for tyrosine phosphorylation, this information may provide insight into possible pharmacological approaches to modify therapeutic regimens by analyzing the status of this protein in tumor samples for a better survival of the cancer patients.

Is All Fair in Law and War? The Ambiguous Principle of Proportionality of Collateral Damage and the CIA Drone Attacks in Pakistan

Tutkielma käsittelee Yhdysvaltain CIAn miehittämättömiä lennokki-iskuja Pakistanissa kansainvälisen humanitaarisen oikeuden suhteellisuusperiaatteen näkökulmasta. Suhteellisuusperiaatteen mukaan aseellisista iskuista saatavan sotilaallisen hyödyn tulee olla suhteellinen verrattuna siviileille aiheutuvaan haittaan. CIAn iskuja Pakistanissa on kritisoitu, että ne eivät täytä suhteellisuusperiaatteen asettamia vaatimuksia. Tutkielmassa perehdytään ensinnäkin selvittämään ne velvollisuudet, jotka suhteellisuusperiaate asettaa hyökkääjille. Sen jälkeen CIAn lennokki-iskuja tutkitaan näiden velvollisuuksien valossa. Tutkielmassa pyritään selvittämään antaako suhteellisuusperiaatteen luomat oikeudelliset velvollisuudet riittävää suojaa Pakistanin siviileille lennokki-iskujen tuhoja vastaan. Lisäksi pyritään selvittämään, onko lennokki-iskuissa viitteitä suhteellisuusperiaatteen vastaisista iskuista. Tutkimusmenetelmänä käytetään positivistista lainopin metodia, jonka avulla selvitetään voimassa olevaa kansainvälisen humanitaarisen tapaoikeuden suhteellisuusperiaatteen sisältöä. Oikeudellisina lähteinä käytetään pääasiassa humanitaarista tapaoikeutta, mutta tulkinnallisena apuna myös kansainvälisiä sopimuksia sekä oikeuden päätöksiä. Lisäksi oikeudellinen kirjallisuus on tutkimuksessa tärkeässä asemassa. Tutkimuksessa päädytään siihen, että suhteellisuusperiaatteen asettamat velvollisuudet hyökkääjälle ovat niin epämääräiset, että ne eivät anna riittävää suojaa siviileille. Ensinnäkin hyökkääjä voi määrittää sotilaallisen hyödyn omien päämääriensä mukaisesti suhteellisuusanalyysissä. Lisäksi kynnys sille, mikä katsotaan suhteellisuusperiaatteen vastaisuudeksi on hyvin epämääräinen ja korkea. Tämän vuoksi varotoimenpiteet iskujen suunnittelussa ovat hyvin tärkeässä asemassa myös suhteellisuusanalyysissä. Kuitenkin jos hyökkääjä edes jossain määrin osoittaa, että on tehnyt iskut hyvässä uskossa niiden laillisuudesta, iskujen katsotaan yleensä olevan suhteellisuusperiaatteen mukaisia. CIAn lennokki-iskuissa Pakistanissa on viitteitä suhteellisuusperiaatteen vastaisuudesta erityisesti ”tunnusmerkki-iskujen” osalta. ”Tunnusmerkki-iskut” johtavat yleensä vain vähäiseen sotilaalliseen hyötyyn aiheuttaen silti siviiliuhreja. Lisäksi erityisesti tunnusmerkki-iskuissa edellytetään korkeampaa tarkkuutta varotoimenpiteissä. Kuitenkin useat siviiliuhrit voivat merkitä sitä, että näitä varotoimenpiteitä ei ole noudatettu iskuissa.

Credit Default Swaps (CDS) y Collateral Debt Obligation (CDO) derivados financieros responsables de la crisis sub-prime de 2008 en Estados Unidos y una guía para el desarrollo del mercado de derivados exóticos en Colombia

La crisis financiera hipotecaria de 2008 en la que se declaró en quiebra el banco de inversión Lehman Brothers, se desarrolló en un ambiente que contemplaba apalancamientos financieros excesivos y el uso de derivados financieros de crédito innovadores. Razón por la cual, a partir del estudio de caso de quiebra de este banco de inversión y el análisis de las causas y consecuencias del ambiente desregulatorio que surgió en Estados Unidos desde la década de los 30 hasta el 2000, se orienta la investigación a indagar sobre lo que sucede en términos regulatorios y empresariales en el mercado de valores colombiano y así lograr definir objetivos que permitan el crecimiento del mercado de derivados exóticos en Colombia bajo un marco de responsabilidad financiera y ética empresarial.