Anticancer activity of modified somatostatin analogs

Somatostatine is een hormoon dat de afgifte van groeihormoon en een aantal andere hormonen (o.a. insuline, glucagon en schildklierhormonen) remt. Het peptide somatostatine bindt specifiek aan receptoren op de cel (sleutel-slot principe), en oefent na internalisatie vervolgens in de cel zijn remmende werking uit. Somatostatine wordt gevormd in de alvleesklier (= pancreas), hypothalamus en in de wand van maag en darm. Veel endocriene tumoren brengen de somatostatinereceptor tot expressie en worden dus in hun hormoon afgifte geremd door somatostatine. Deze remmende werking heeft ertoe geleid om patiënten met ziekten veroorzaakt door te hard werkende klieren of tumoren met somatostatine-receptoren te behandelen met somatostatine. Somatostatine is zelf echter niet geschikt voor therapie doordat het snel wordt afgebroken in het lichaam. Vandaar dat er soortgelijke peptiden (analogen) zijn gemaakt die veel stabieler zijn, een voorbeeld hiervan is octreotide. Vervolgens is octreotide radioactief gemaakt om receptorpositieve tumoren zichtbaar te maken in het lichaam met behulp van een gammacamera. In 1994 werd 111In-DTPA-octreotide (OctreoScan®) goedgekeurd door de “U.S. Food and Drug Administration” (FDA) voor diagnostisch gebruik op patiënten met neuroendocriene tumoren. Tot op de dag van vandaag is OctreoScan® de “Gouden Standaard” voor de visualisatie van neuroeendocriene tumoren. Verder onderzoek op dit gebied heeft geleid tot de introductie van Peptide Receptor Radionuclide Therapie (PRRT), door gebruik te maken van radionucliden met bètastraling (90Y en 177Lu), die gekoppeld worden aan deze somatostatine analoga. Het doel van dit proefschrift was in eerste instantie om meer inzicht te krijgen in de therapeutische mogelijkheden van gelabelde somatostatine analogen in vitro en in vivo. Vervolgens wilden we de radionucliden therapie met somatostatine analogen verbeteren door dit te combineren met een factor waarvan bekend is dat het celdood initieert in de cel. Aangezien de respons van tumorcellen op PRRT afhankelijk is van de stralingsgevoeligheid van deze cellen hebben we de stralingsgevoeligheid van CA20948 tumorcellen, dit is een rattenpancreas tumorcellijn welke de somatostatinereceptor subtype 2 (sst2) tot expressie brengt, in vitro bepaald met behulp van een kolonievormende assay na bestraling met externe radiotherapie (XRT). Het is echter te verwachten dat de resultaten van bestraling met een hoog dosistempo, XRT, niet representatief is voor bestraling met een laag dosistempo, radionucliden therapie (RT), bestraling. Daarom hebben we de overleving van CA20948 tumorcellen in vitro na een toenemende dosis van XRT of RT met elkaar vergeleken (Hoofdstuk 2). We hebben een dosisafhankelijke reductie in tumorceloverleving waargenomen, welke, bij lage doses, dezelfde was voor XRT als RT. Dus, ondanks de enorme verschillen in dosistempo, zijn de tumorceldodende effecten van RT ongeveer even effectief als die van XRT bij doses van 1 en 2 Gy, de laatste is de dagelijks toegediende dosis bij gefractioneerde externe radiotherapie bestraling. Bij hogere doses was RT minder effectief dan XRT. Voor XRT, de kwadratische ten opzichte van de lineaire component ratio (a/ß) voor de CA20948 cellijn was 8.3 Gy, terwijl deze ratio voor RT uitgerekend werd op 86.5 Gy. In hoofdstuk 3 is de therapeutische potentie van 111In-DTPA-octreotide geëvalueerd. Aangezien 111In, naast gammastraling, ook therapeutische Auger en interne conversie elektronen, met een middel tot korte dracht (0.02-10 µm, 200-550 µm, respectievelijk), uitzendt, wordt 111In-DTPA-octreotide ook gebruikt voor PRRT. Als eerste (Hoofdstuk 3.1) zijn de therapeutische effecten van 111In-DTPA-octreotide in een kolonievormend model onderzocht. In dit model hebben we gediscrimineerd tussen the effecten van de Auger elektronen en interne conversie elektronen bij PRRT. 111In-DTPA-octreotide kon de tumorgroei in dit model volledig remmen. De effecten waren afhankelijk van de incubatietijd, de hoeveelheid straling en de gebruikte specifieke activiteit. Dezelfde concentraties van 111In-DTPA, welke niet kan internaliseren in somatostatine receptorpositieve tumorcellen, hadden geen effect op de tumorgroei. Een overmaat aan ongelabeld octreotide (10-6 M) kon de tumorgroei remmen tot 60% van de controlegroei; de toevoeging van gelabeld peptide 111In-DTPA-octreotide (10-9 M) met een overmaat aan ongelabeld octreotide (10-6 M) kon de tumorgroei niet verder remmen. Deze in vitro experimenten laten zien dat the therapeutische effecten van 111In afhankelijk zijn van internalisatie, hierdoor kunnen de Auger elektronen men hun korte dracht de kern bereiken. Onze resultaten geven verder weer dat de PRRT-resultaten receptorgemedieerd zijn. Vervolgens hebben we de radiotherapeutische effecten van verschillende doses 111In-DTPA-octreotide in vivo in Lewis ratten, die een kleine (= 1 cm2) of een grote (= 8 cm2) somatostatine receptorpositieve CA20948 tumor hadden, onderzocht. Bovendien hebben we de somatostatine receptordensiteit op de tumor voor en na behandeling met radionuclide therapie onderzocht (Hoofdstuk 3.2) De resultaten laten fantastische radiotherapeutische effecten zien van 111In-gelabeld octreotide in dit rattenmodel. Genezing (tot 50%) werd gevonden in de dieren met een kleine tumor na ten minste drie injecties met 111 MBq of één injectie met 370 MBq 111In-DTPA-octreotide, wat leidde tot een dosis van 6.3 – 7.8 mGy/MBq (1 – 10 g tumor). In de groep ratten met een grote tumor waren de effecten minder duidelijk, hier werd alleen een partiele respons gevonden. Een mogelijke verklaring voor de verschillende effecten na 111In therapie in grote versus kleine tumoren kan zijn dat er een toename is in de groei van somatostatine receptornegatieve cellen door een gebrek aan crossfire. We hebben daarom de expressie van de somatostatine receptor onderzocht voor en na radionuclide therapie met een In-111 gelabeld somatostatine analoog. In dit onderzoek hebben we een duidelijke expressie gevonden van de somatostatine receptor subtype 2 (sst2) in zowel de controle tumoren als in de tumoren die behandeld zijn met 111In. Een significant hogere receptordensiteit werd er gevonden op de tumoren die na een tumorverkleining door PRRT weer zijn gaan groeien in vergelijking met de onbehandelde tumoren. We hebben hieruit geconcludeerd dat de behandeling van tumoren met radionuclide therapie met 111In-gelabelde somatostatin analogen zo vroeg mogelijk gestart moet worden. Ook interessant is, bij somatostatine receptorpositieve tumoren, dat radioactief gelabelde somatostatine analogen te gebruiken na chirurgie om eventuele metastasen te behandelen. Ten slotte hebben we laten zien dat de somatostatine receptor nog steeds aanwezig is na PRRT en zelfs is toegenomen in densiteit bij tumoren die eerst kleiner zijn geworden en vervolgens weer zijn gaan groeien. De toename in de somatostatine receptordensiteit leidt tot een hogere opname van de radioactief gelabelde peptiden bij therapeutische toepassingen, wat herhaalde injecties met radioactief gelabelde peptiden effectiever maakt. In hoofdstuk 4 zijn de therapeutische effecten van de somatostatine analogen Tyr3-octreotide en Tyr3-octreotate, gelabeld met de bètastralers 177Lu en 90Y, onderzocht in de ratten tumorcellijn CA20948 met behulp van een kolonievormende assay (Hoofdstuk 4.1). 177Lu-DOTA-Tyr3-octreotate kon de tumorgroei volledig remmen, de effecten waren afhankelijk van de hoeveelheid straling, de incubatietijd en de gebruikte specifieke activiteit. Dezelfde concentratie van 177Lu-DOTA, dit bindt niet aan de tumorcellen en kan dus niet internaliseren, had een duidelijk minder effect op de tumorceloverleving. De beide analogen Tyr3-octreotide en Tyr3-octreotate, gelabeld met 177Lu of 90Y, konden de tumorgroei op een dosisafhankelijke manier controleren. Bij alle gebruikte concentraties kon het radiogelabelde analoog Tyr3-octreotate de tumorgroei beter remmen dan Tyr3-octreotide. Dit komt overeen met het feit dat Tyr3-octreotate een hoger affiniteit heeft voor de sst2-receptor dan Tyr3-octreotide, wat leidt tot een hogere concentratie aan celgebonden radioactiviteit en daardoor een hogere stralingsdosis op de tumorcellen. Tyr3-octreotate gelabeld met 177Lu of 90Y is dus een veelbelovend analoog voor PRRT. Vervolgens zijn de therapeutische effecten van 177Lu-DOTA-Tyr3-octreotate onderzocht op somatostatine receptorpositieve CA20948 lever micrometastasen (Hoofdstuk 4.2). Ratten die behandeld zijn met 177Lu-DOTA-Tyr3-octreotate hadden een duidelijk betere overleving dan de controle dieren (onbehandeld), waardoor dit een veelbelovende nieuwe therapie is voor (uitzaaiingen van) somatostatine receptorpositieve tumoren. In hoofdstuk 5 is een studie beschreven die erop gericht is een nieuw radiofarmacon te ontwikkelen en te evalueren voor de behandeling van tumoren die sst2 tot expressie brengen. Dit nieuwe radiofarmacon bestaat uit 2 peptiden (een hybride peptide); een somatostatine-receptor gericht peptide, octreotate; en een peptide dat celdood initieert, RGD (arginine-glycine-aspartaat). Tevens bevat dit nieuwe radiofarmacon een chelator (DTPA) zodat het makkelijk radioactief gelabeld kan worden met 111In. Biodistributie studies lieten zien dat dit nieuwe radiofarmacon goed bindt aan de somatostatine receptor. Na binding aan de receptor wordt het radiofarmacon geïnternaliseerd in de cel en kan het RGD-peptide celdood initiëren. Internalisatie-experimenten in sst2-positieve tumorcellen met het radiogelabelde hybride peptide (RGD-111In-DTPA-octreotate) laten zien dat de internalisatie hiervan snel verloopt en dat deze geblokkeerd kan worden met een overmaat aan ongelabeld octreotide, hetgeen duidt op een sst2-specifieke opname. De tumoropname van RGD-111In-DTPA-octreotate in ratten kwam overeen met de in vitro data en was vergelijkbaar met die van het radioactief gelabeld Tyr3-octreotate. Een minpunt van dit nieuwe hybride peptide was de hoge opname en retentie van de radioactiviteit in de nieren, dit limiteert namelijk de therapeutische dosis die gegeven kan worden, aangezien de nieren kritieke organen zijn bij radionuclide therapie met somatostatine analogen die gelabeld zijn met ß-emitters (Hoofdstuk 5.1). Therapeutische effecten van het hybride peptide RGD-DTPA-octreotate zijn geëvalueerd in vergelijking met die van RGD en Tyr3-octreotate in een in vitro kolonievormende assay, alle peptiden waren radioactief gelabeld met 111In. Vervolgens is de caspase-3 activiteit bepaald (Hoofdstuk 5.2). De therapeutische effecten waren (in volgorde van het minst effectief naar het meest effectief) 111In-DTPA-RGD < 111In-DTPA-Tyr3-octreotate < RGD-111In-DTPA-octreotate. Ook de hoogste toename van caspase-3 activiteit werd gevonden na behandeling met RGD-DTPA-octreotate. RGD-111In-DTPA-octreotate heeft dus een duidelijk beter therapeutisch effect dan 111In-DTPA-RGD en 111In-DTPA-Tyr3-octreotate, waarschijnlijk door een toename in de initiatie van celdood veroorzaakt door een toename in caspase-3 activiteit. In hoofdstuk 5.3 hebben we de biodistributie van RGD-111In-DTPA-octreotate en 125I-RGD-octreotate geëvalueerd, tevens hebben we het therapeutische effect van het ongelabelde peptide RGD-DTPA-octreotate in vitro onderzocht. Aangezien de biodistributie een hoge nieropname liet zien hebben we therapeutische effecten van het ongelabelde hybride peptide, RGD-DTPA-octreotate, in de volgende sst2-positieve cellijnen onderzocht; CA20948, AR42J en chinese hamster ovary (CHO) cellijn. De resultaten hiervan lieten zien dat er een significante toename in caspase-3 was activiteit in vergelijking met RGD en Tyr3-octreotate in alle cellijnen die gebruikt zijn. Vervolgens hebben we, om de nieropname te verlagen in het lichaam, de biodistributie van gejodeerd RGD-octreotate zonder de chelator DTPA onderzocht. 125I-RGD-octreotate liet inderdaad een veel lagere nieropname zien in vergelijking met RGD-111In-DTPA-octreotate. Bovendien was de affiniteit voor de somatostatine receptor van RGD-octreotate toegenomen ten opzichte van RGD-DTPA-octreotate (IC50 waarde van 1.4×10-8M vs 9.4×10-8M, respectievelijk). Ten slotte bleek dat RGD-octreotate, zonder de chelator DTPA, ook caspase-3 kan activeren. Dus het concept om tumoren, die somatostatine receptoren tot expressie brengen, te behandelen kan ook toegepast worden met behulp van somatostatine analogen die gekoppeld zijn aan chemotherapeutische middelen, dit is verder beschreven in Hoofdstuk 5.4. De ontwikkeling van hybride moleculen kan een nieuwe methode zijn voor de strijd tegen kanker.There has been an exponential growth in the development of radiolabeled peptides for diagnosis and therapeutic applications in oncology. Peptides radiolabeled with .-emitters can be used to visualize receptor-positive cells in vivo. In 1994 111In-DTPA-octreotide (OctreoScan®) received FDA approval as the first product of its kind, and to this day remains the “Gold Standard” in somatostatin receptor scintigraphy. Research continued in this area by introducing peptide receptor radionuclide therapy (PRRT) using Auger electron (111In) and ß particle (90Y and 177Lu) emitting radionculides. The aim of this thesis was firstly to receive further insight in the therapeutic potential of somatostatin labeled analogs in vitro and in vivo. Secondly, we wanted to improve the potential of PRRT with somatostatin analogs by introducing the combination with an apoptosis-inducing factor. Since the response of tumor cells to PRRT is dependent on their radiosensitivity we determined the radiosensitivity of CA20948 tumor cells, rat pancreatic tumor cells expressing the somatostatin receptor (sst), by using clonogenic survival assays after high-dose-rate external-beam radiotherapy (XRT) in vitro. It could be expected however that results of high-dose-rate XRT are not representative for those after low-dose-rate radionuclide therapy (RT), such as PRRT. Therefore, we compared clonogenic survival in vitro in CA20948 tumor cells after increasing doses of XRT or RT, the latter using 131I (Chapter 2). We observed a dose-dependent reduction in tumor-cell survival, which, at low doses, was similar for XRT and RT. For high-dose-rate XRT, the quadratic over linear component ratio (a/ß) for CA20948 was 8.3 Gy, whereas that ratio for low-dose-rate RT was calculated to be 86.5 Gy. So, despite the huge differences in dose rate, RT tumor cell-killing effects were approximately as effective as those of XRT at doses of 1 and 2 Gy, the latter being the common daily dose given in fractionated external-beam therapies. At higher doses, RT was less effective than XRT. In chapter 3 the therapeutic potential of 111In-DTPA-octreotide was evaluated. Since 111In emits not only gamma-rays, but also therapeutic Auger and internal conversion electrons with a medium to short tissue penetration (0.02-10 µm, 200-550 µm, respectively), 111In-DTPA-octreotide is also being used for PRRT. First (Chapter 3.1), the therapeutic effects of 111In-DTPA-octreotide in a single-cell model were investigated. In this single-cell model we discriminated between the effects of the Auger electrons and internal conversion electrons in PRRT. In this in vitro system 111In-DTPA-octreotide could completely control tumor growth. The effects were dependent on incubation time, radiation dose, and specific activity used. Similar concentrations of 111In-DTPA, which is not internalized into somatostatin-positive tumor cells, did not influence tumor survival. Excess unlabeled octreotide (10-6 mol/L) could decrease tumor cell survival to 60% of control; the addition of the radiolabeled peptide 111In-DTPA-octreotide (10-9 mol/L) plus an excess of unlabeled (10-6 mol/L) octreotide, did not further decrease survival. So, these in vitro studies show that the therapeutic effect of 111In is dependent on internalization, enabling the Auger electrons with their very short particle range to reach the nucleus. Our results also indicate that the PRRT-effects were receptor-mediated. Subsequently, we investigated the radiotherapeutic effect of different doses of 111In-DTPA-octreotide in vivo in Lewis rats bearing small (= 1 cm2) or larger (= 8 cm2) somatostatin receptor-positive rat pancreatic CA20948 tumors. In addition, we investigated the somatostatin receptor density on the tumors before and after radionuclide therapy (Chapter 3.2). The results showed impressive radiotherapeutic effects of 111In-labeled octreotide in this rat tumor model. Cure (up to 50%) was found in the animals bearing small tumors after at least three injections of 111 MBq or a single injection of 370 MBq 111In-DTPA-octreotide, leading to a dose of 6.3 – 7.8 mGy/MBq (1 – 10 g tumor). In the rats bearing the larger tumors the effects were much less pronounced and only partial responses were reached in these groups. A possible explanation for the various responses found is the increase of somatostatin receptor-negative cells, due to the lack of crossfire. We therefore investigated the somatostatin receptor expression before and after radionuclide therapy with an In-111 labeled somatostatin analog. In this study we found a clear somatostatin receptor subtype 2 (sst2) expression both in the control and in the tumors treated with 111In. A significantly higher tumor receptor density was found when the tumor re-grew after an initial decline in size after low dose PRRT in comparison with untreated tumors. We concluded that radionuclide-therapy with 111In-labeled somatostatin analogs is feasible but should preferably start as early as possible during tumor development. One might also consider the use of radiolabeled somatostatin analogs in an adjuvant setting after surgery of somatostatin receptor-positive tumors to eradicate occult metastases. Finally we showed that PRRT led to a significant increase in somatostatin receptor density, when the tumors re-grew after an initial decline in size after PRRT. The increase in the somatostatin receptor density will lead to a higher uptake of the radiolabeled peptides in therapeutic applications, making repeated injections of radiolabeled peptides more effective. In chapter 4 the therapeutic effects of the somatostatin analogs Tyr3-octreotide and Tyr3-octreotate radiolabeled with the ß- particle emitters 177Lu or 90Y were evaluated in an in vitro colony-forming assay using the rat pancreatic tumor cell line CA20948 (Chapter 4.1). 177Lu-DOTA-Tyr3-octreotate could reduce tumor growth with 100% and effects were dependent on radiation dose, incubation time, and specific activity used. Similar concentrations of 177Lu-DOTA, which does not bind to the tumor cells, had a less pronounced effect on tumor cell survival. Both Tyr3-octreotide and Tyr3-octreotate labeled with either 177Lu or 90Y, using DOTA as chelator, were able to control tumor growth in a dose-dependent manner. In all concentrations used radiolabeled Tyr3-octreotate showed a higher percentage tumor cell kill compared to radiolabeled Tyr3-octreotide, labeled with 177Lu or 90Y. This is in accordance with the higher affinity of Tyr3-octreotate for the sst2-receptor compared to Tyr3-octreotide, leading to a higher amount of cell-associated radioactivity, resulting in a significantly higher tumor radiation dose. So, Tyr3-octreotate labeled with 177Lu or 90Y is the most promising analog for PRRT. Subsequently, the anti-tumor effects of 177Lu-DOTA-Tyr3-octreotate on sst receptor positive CA20948 micrometastases in the liver were investigated (Chapter 4.2). Rats treated with 177Lu-DOTA-Tyr3-octreotate showed a significantly better survival in a rat liver micrometastic model setting, making it a very promising new treatment modality for sst receptor positive disseminated disease. In chapter 5 a study is described that aimed to develop and evaluate a new radiopharmaceutical for the treatment of cancers that overexpress sst2. The new radiopharmaceutical is composed of a somatostatin receptor-targeting peptide, a chelator (DTPA) to enable radiolabeling, and an apoptosis inducing RGD (arginine-glycine-aspartate) peptide moiety. Biodistribution studies showed that the receptor-targeting peptide portion of the molecule, Tyr3-octreotate, binds specifically to the sst2. Because of the rapid endocytosis of the somatostatin receptor the entire molecule can thus be internalized, allowing the RGD portion to activate intracellular caspases, which in turn promotes apoptosis. Internalization experiments in vitro into sst2-positive tumor cells of the radiolabeled hybrid peptide appeared to be a rapid process and could be blocked by an excess of unlabeled octreotide, indicating an sst2-specific process. Tumor uptake of radiolabeled RGD-DTPA-octreotate in vivo in rats was in agreement with the in vitro data and comparable to that of radiolabeled Tyr3-octreotate. A drawback of the new hybrid compound was high renal uptake and retention of radioactivity, limiting the therapeutic dose that can be administered, as the kidneys are critical organs in radionuclide therapy using somatostatin analogs labeled with beta particle emitting radionuclides (Chapter 5.1). Tumoricidal effects of the hybrid peptide RGD-DTPA-octreotate were evaluated in comparison with those of RGD and Tyr3-octreotate in an in vitro colony-forming assay, the compounds were all radiolabeled to 111In. Subsequently caspase-3 activation was determined (Chapter 5.2). Tumoricidal effects were found for 111In-DTPA-RGD < 111In-DTPA-Tyr3-octreotate < RGD-111In-DTPA-octreotate. Also, the highest increase in caspase-3 levels was found with RGD-111In-DTPA-octreotate. Concluding, RGD-111In-DTPA-octreotate has a more pronounced tumoricidal effect than 111In-DTPA-RGD and 111In-DTPA-Tyr3-octreotate, because of increased apop

Forecasting regional growth: the MASST model

Nowadays, forecasting regional growth is not possible without taking into account the recent economic dynamics at national and supranational level. In fact, the particular focus of the European Union on sovereign debts and deficits imposed by the economic slowdown, the macroeconomic trends that emerged as a result of the crisis and, last but not least, new politically sensible decisions concerning the future of the European Union play a role in explaining the remarkable industrial and geographic heterogeneity in the response to the crisis and the persistence of some of the contraction-induced effects in some countries and regions. All this introduces complexity in the way regional economic growth can be modelled for forecasting purposes. The MASST model is a regional econometric growth model built to simulate regional growth scenarios in the medium and long run (typically, over a 15–20‑year time horizon), taking into consideration also macroeconomic aspects; in its estimation step, in fact, it explains regional growth as the result of national macroeconomic trends and regional growth assets at the same time. This paper aims to present the model and its interpretative power by merging national macroeconomic trends and the long-term regional structure. Particular emphasis will be given to the outcomes of two recent simulations for Polish regions

Design of Sliding Mode Techniques for a CMG-based Testbed Attitude Control System

Precise pointing accuracy and rapid maneuvering are two key features for attitude control missions of small spacecraft. Control moment gyroscopes (CMGs) are applied as ideal actuator for large torque output capability but are usually limited due to the problem of inherent mechanical singularity. This paper proposes a robust attitude control methodology, based on Sliding Mode Control (SMC) techniques, in presence of CMG practical restrictions and disturbances. Two second-order SMC techniques are designed, to guarantee accuracy and limited convergence time. Moreover, attitude control torques are generated by means of four single gimbal CMGs in pyramidal configuration, considering the design of an experimental testbed. The effectiveness of the proposed methodologies are shown in simulations, for different mission scenarios, including singularity points

Territorial capital and regional growth: Increasing returns in cognitive knowledge use

Knowledge drives the growth of nations and regions in a competitive space-economy. Hence, we would expect a strong correlation between investments in R&D, knowledge and learning processes, on the one hand, and productivity increases, on the other. However, the empirical evidence shows consistent discrepancies between knowledge inputs and economic performance across geographical units. This paper addresses this intriguing issue at the regional level, by highlighting both theoretically and empirically the strategic importance played by cognitive elements as part of “territorial capital” in mediating between knowledge production and regional growth. The main proposition of the paper, subject to empirical testing, is that cognitive elements as part of territorial capital magnify the contribution of knowledge by determining the formation of increasing returns to knowledge exploitation

Territorial scenarios in Europe: Growth and disparities beyond the economic crisis

Up to the start of the present economic crisis (2008), Europe was characterized by a clear trend of convergence in the GDP level of European countries, which was able to counterbalance the opposite trend in intra-national disparities that took place in many countries – namely those with a more recent accession to the Union. The economic downturn of the last years, however, has brought this process of convergence to a halt, mainly as a consequence of the tight austerity policies imposed to many southern European countries. This evidence, recognized by the European Union in the last Cohesion Report (“the crisis has reversed the process of convergence of regional GDP per head and unemployment within the EU”) brought to the fore the relevance of macroeconomic policies in regional development. Therefore in this paper, with the help of a newly built macroeconomic and regional forecasting model (MASST), the future of regional convergence / divergence in the EU is explored through four scenarios: a baseline one, recognizing the clear break of the crisis and three exploratory scenarios, depicting in a consistent way three different “territorial” strategies: supporting large metropolises vs. cities of second and third rank, vs. peripheral and lagging regions. Interestingly enough, the “cities” scenario proves to be at the same time the most cohesive and the most expansionary, shedding some doubts on the traditional equity/efficiency trade-off through an intermediate strategy based on the exploitation of a diffused territorial capital. Overall, diverging regional processes are forecasted from now to 2030

High Survivorship With a Titanium-encased Alumina Ceramic Bearing for Total Hip Arthroplasty

Background Although ceramic-on-ceramic bearings for total hip arthroplasty (THA) show promising results in terms of bearing-surface wear, fracture of the bearing, insertional chips, and squeaking remain a concern. Questions/purposes Our primary objective of this report was to determine overall survivorship of a titanium- encased ceramic-on-ceramic bearing couple. Our secondary objectives were to evaluate for ceramic fracture, insertional chips, osteolysis, and device squeaking. Methods Six surgeons at six institutions implanted 194 patients (209 hips) with an average age of 52 years with cementless hips and alumina ceramic bearings. One hun- dred thirty-seven patients (146 hips) have 10-year followup (70%). We determined Kaplan-Meier survivorship of the bearing surface and implant system and collected radio- graphic and clinical data to evaluate for osteolysis and squeaking. Results Survivorship using revision for any reason as the end point was 97% at 10 years and survivorship end point bearing surface failure or aseptic loosening of 99%. There was one ceramic insert fracture (0.5%), there were no insertional chips, there was no visible osteolysis on AP and lateral radiographs, and there was a 1% patient- self-reported incidence of squeaking at the last clinical followup. Six hips underwent revision (3.7%). Conclusions Ceramic bearings for THA with a titanium- encased insert have high survivorship at 10 years followup and a fracture risk of 0.5%. We found at last followup on routine radiographs no evidence of osteolysis, and no patient has been revised for squeaking or has reported dissatisfaction with the clinical result because of noise. Level of Evidence Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Periprosthetic Fractures Around a Cementless Hydroxyapatite-coated Implant: A New Fracture Pattern Is Described

Background Periprosthetic fractures can occur both intraoperatively and postoperatively with implantation of cementless tapered stems. Questions/purposes In a large cohort of patients receiving cementless, proximally hydroxyapatite-coated femoral implants, we answered the following questions: What was the incidence of intraoperative and postoperative fractures associated with the implant? What were the fracture patterns as classified by the Vancouver classification system? Did the Vancouver classification represent the fracture patterns found? How were the fractures treated and what were the treatment outcomes; that is, how many fractures healed and did the stems osseointegrate? Methods We evaluated 1039 hips (932 patients) from three prospective studies. The hips were divided into three groups: no fractures, intraoperative fractures, and postoperative fractures. Demographic differences among the groups were noted. Postoperative fractures were classified using the Vancouver classification system. We judged stem stability using Engh’s criteria and fracture union was determined by the treating surgeon and confirmed by the authors. Results We identified 58 periprosthetic fractures in the 1039 hips (5.6%): 38 intraoperative (3.7%) and 20 postoperative (1.9%). Eleven of the postoperative fractures were classifiable by the original Vancouver classification system and nine were of the newly described “clamshell” variety, not classifiable by this system. No intraoperative fractures extended below the lesser trochanter. Twenty-five of these fractures were treated with a single cable or cerclage wire. The remaining received no specific treatment. Of the 20 postoperative fractures, five were treated nonoperatively. All stems osseointegrated. Conclusions Both intraoperative and postoperative fractures can be managed with success when the stem is stabilized or found to be osseointegrated. An adjustment to the Vancouver classification is suggested to include the clamshell fracture, which has not been previously described. Level of Evidence Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence