bluuebunny/crossref_metadata_2025_split huggingface dataset:
Problems with credit rating and reporting systems in Mexico: A barrier to North America's full economic development?
Authors: Rose Peter S. 
Published: April 2007

AbstractIn many regions of the globe today outside the US and Canada, existing networks for evaluating borrowers' credit histories, for recording borrowers' pledges of assets backing loans, and for the legal enforcement of creditor claims are often poorly developed. Inside North America these problems with credit information flows and legal enforcement systems are most evident inside Mexico, where credit reporting networks and the courts work under a somewhat different set of rules than in Canada and the United States. A national mail survey of more than 300 US banks lending across international boundaries into Mexico found that many US bankers have reservations about the credibility of credit reporting and credit security systems inside Mexico. If these reservations persist, they can lead to a fundamental restructuring of that developing nation's industry that could discourage international capital inflows and curtail the emergence of small business. Indeed, unless current credit information flows are more fully integrated and are of more uniform quality throughout North America, the North American Free Trade Agreement (NAFTA) is likely to continue to fall short of its promise of significant job growth and improved living standards throughout the continent. © 1997 John Wiley & Sons, Inc.
Synthese und Charakterisierung von Methyldialkoxogallanen MeGa(OR)2 (R = Et, nBu)
Authors: Chamazi Navabeeh Nami , Heravi Majid M. , Neumüller Bernhard 
Published: April 2007

AbstractSynthesis and Characterization of Methyldialkoxogallanes MeGa(OR)2(R = Et, nBu)GaMe3 reacts with ROH (R = Et, nBu) to give the methyldialkoxogallanes MeGa(OR)2 [R = Et (1), nBu (2)] under evolution of methane in boiling toluene. 1 and 2 were characterized by NMR and IR spectroscopy as well as by X‐ray analyses. According to the structural investigations both compounds form centrosymmetrical dimers which are connected to infinite chains along [100] (1) or [001] (2).
Synthese und Struktur der Cluster [Cu50Se24(S‐thiaz)2(dppm)10] und [Cu48Se24(S‐thiazH)2(dppm)10]
Authors: Fuhr Olaf , Fernandez‐Recio Lucia , Castiñeiras Alfonso , Fenske Dieter 
Published: April 2007

AbstractSynthesis and Structure of the Clusters [Cu50Se24(S‐thiaz)2(dppm)10] and [Cu48Se24(S‐thiazH)2(dppm)10]The reaction of copper(I) acetate with bis(diphenylphosphanyl)methane (dppm), 2‐mercaptothiazoline (S‐thiazH) and Se(SiMe3)2 in DME leads to the formation of [Cu50Se24(S‐thiaz)2(dppm)10] (1). In some rare cases additionally another cluster, [Cu48Se24(S‐thiazH)2(dppm)10] (2), is formed. Both clusters have nearly equal molecular structures; they only differ in the area, where the 2‐mercaptothiazoline ligands are located. In their copper selenium core both show structural features that are typical for the low temperature phase of binary Cu2Se.
Synthese und Kristallstrukturen von [p‐Me3NC6H4HgOC(O)Me][MeOSO3] und [(p‐Me3NC6H4)2Hg][HgI4]
Authors: Kuhn Norbert , Abu‐Salem Qutaiba , Maichle‐Mößmer Cäcilia , Steimann Manfred 
Published: April 2007

AbstractSyntheses and Crystal Structures of [p‐Me3NC6H4HgOC(O)Me][MeOSO3] and [(p‐Me3NC6H4)2Hg][HgI4]The carbene complexes [p‐Me3NC6H4HgOC(O)CH3][MeOSO3] (5) and [(p‐Me3NC6H4)2Hg][HgI4] (7) are obtained by alkylation of Me2NC6H4HgOC(O)Me (4) with Me2SO4 or MeI. The crystal structures of 5 and 7 reveal the expected presence of Hg‐C single bonds in both complexes.
Preparation and Characterization of Boron Chelates with Pyridoxine. The Crystal and Molecular Structures of [B(H2pdn)(Hpdn)]·H2O and [Ph2B(H2pdn)] (H3pdn = Pyridoxine)
Authors: de Sousa Adriana T. , Bessler Karl E. , Lemos Sebastia–o S. , Gomes Fernanda B. , Casagrande Gleison A. , Schulz Lang Ernesto 
Published: April 2007

AbstractThe 1:2 complex of boric acid with pyridoxine (1) crystallizes from aqueous solution as monohydrate in the triclinic space group ${\rm P}{\bar 1}$. The molecular structure of 1 corresponds to the expected bis‐chelate containing two non‐equivalent pyridoxinate ligands, one of them being dianionic and the other one monanionic, betain‐like with a protonated pyridine nitrogen atom. In the crystal structure hydrogen bonding, involving the water molecule, provides a supramolecular arrangement in form of sheets parallel to [011]. The 1H and 13C NMR spectra of 1 reveal a fast proton exchange between the two ligands in aqueous solution. Two new boron‐pyridoxine complexes [Ph2B(H2pdn)] (2) and [B(C2O4)(H2pdn)] (3) (H3pdn = pyridoxine) were prepared and characterized. In The crystal structure of 2 (monoclinic, P21/c) the molecules are linked to chains by N‐H···O hydrogen bonds along the b axis.
Synthesis, Crystal Structure and Supramolecular Organization of the 1D Coordination Polymer [Cu(HCOO)2(4‐bpytm)], (4‐bpytm = Bis(4‐pyridylthio)methane)
Authors: Carballo Rosa , Covelo Berta , García‐Martínez Emilia , Lago Ana B. , Vázquez‐López Ezequiel M. 
Published: April 2007

AbstractThe reaction of the flexible pyridyl dithioether ligand Bis(4‐pyridylthio)methane (4‐bpytm) with copper(II) formiate led to the formation of the coordination polymer [Cu(HCOO)2(4‐bpytm)]n, which has been characterized structurally. The copper atom is in a square‐planar environment and 4‐bpytm acts as an N,N′‐bis(monodentate) bridging ligand creating an onedimensional polymeric arrangement. The formiate ligand plays a key role in the supramolecular organization of the chains via CHformiate…Oformiate and CH4bpytm…Oformiate hydrogen bonds.
Synthesis and Characterization of Vanadium(IV) and (V) Complexes with 2‐Hydroxy‐acetophenone‐semicarbazone (H2hasc) as Ligand. X‐Ray Crystal Structures of [VO2(H2hasc)] and [VO2(Hhasc)]
Authors: da S. Maia Pedro Ivo , Deflon Victor M. , de Sousa Gerimário F. , Lemos Sebastia–o S. , Batista Alzir A. , Nascimento Otaciro R. , Niquet Elke 
Published: April 2007

AbstractThree novel vanadium complexes with pharmacologically active ligands were synthesized and characterized: [VIVO(acac)(Hhasc)], [VIVO2(H2hasc)], and [VVO2(Hhasc)], where H2hasc = 2‐Hydroxy‐acetophenone‐semicarbazone. The analytical methods used included FTIR, 1H‐, 13C‐, 51V‐NMR and EPR spectroscopies, elemental analysis and X‐ray diffractometry from single crystals. The crystal and molecular structures of [VIVO2(H2hasc)] and [VVO2(Hhasc)] were determined. [VIVO2(H2hasc)] crystallizes monoclinic [P21/c, Z = 4, a = 783.4(2), b = 1024.9(2), c = 1365.5(3) pm, β = 99.506(14)°]. The (VO2)2+ core is coordinated to a neutral O,N,O‐tridentate unit of the H2hasc ligand, with the vanadium atom showing a square pyramidal coordination sphere. In the crystal of [VVO2(Hhasc)], triclinic [${\rm P}{\bar 1}$, Z = 4, a = 858.73(11), b = 967.39(5), c = 1318.63(12) pm, α = 97.423(5), β = 101.590(6), γ = 98.144(5)°], two symmetry independent (VO2)+ cores are observed. Each of them coordinates to a monodeprotonated Hhasc− unit, in a O,N,O‐tridentate mode. One assumes a square pyramidal geometry for the pentacoordinate vanadium(V) center. An additional interaction is observed for the other one, involving the phenolate oxygen atom from a symmetry related unit, resulting in a [5+1]‐coordination number for the transition metal atom.
Zr50Sc12O43N50 and Zr3Sc4N8 – Synthesis, Neutron Powder Diffraction and Raman Spectroscopy
Authors: Martinez Meta N. J. , Schweda E. , Boysen H. , Haug A. , Chassé T. , Hoelzel M. 
Published: April 2007

AbstractThe nitridation of Zr50Sc12O118 (Zr0.807Sc0.193O1.90), an anion deficient fluorite related compound, with ammonia yields at 1100 °C a green product with composition Zr1.613Sc0.387O1.387N1.613. This compound crystallizes cubic in space group $Ia{\bar 3}$ (a = 1007.8(5) pm) and is isostructural to Bixbyite with statistical distribution of Zr/Sc at the cation and of O/N at the anion sites. These are the results of Rietveld refinements from a powder neutron diffraction experiment. If Zr3Sc4O12 (Zr0.429Sc0.571O1.714), an educt with another Zr/Sc ratio, is nitridated with ammonia the reaction path shows again the formation of a compound with a bixbyite structure, but finally at 1200 °C a red nitride with the composition Zr3Sc4N8 (Zr0.375Sc0.5N) is formed. This compound has a cation deficient NaCl type structure (space group is $Fm{\bar 3}m$) with a = 452.8(1) pm. Neutron diffraction revealed again no ordering on the cation sites. Both compounds show an unperturbed N≡N stretching frequency in their Raman spectrum at 2327 cm−1. Zr3Sc4N8 exhibits at 1552 cm−1 a second sharp line which was assigned to a N22− moiety.
Zink‐katalysierte Alkoholyse von β‐Lactonen und aktivierten β‐Lactamen
Authors: Groß F. , Brombacher H. , Vahrenkamp H. 
Published: April 2007

AbstractZinc‐Catalyzed Alcoholysis of β‐Lactones and Activated β‐LactamsIn the presence of methanol or ethanol the complex TpPh,MeZn‐OH acts as a catalyst for the ring opening of β‐butyrolactone and N‐nitrophenyl substituted β‐propiolactams, resulting in the formation of the esters of β‐hydroxybutyric acid and N‐substituted β‐aminopropionic acids.
Alkali Salts of 5‐Aminotetrazole – Structures and Properties
Authors: Ernst Veronika , Klapötke Thomas M. , Stierstorfer Jörg 
Published: April 2007

AbstractAlkali salts of 5‐aminotetrazole (5‐At) are common intermediates in synthesis of alkylated aminotetrazoles and their derivatives and can also be used as coloring agents in modern pyrotechnics, due to their high nitrogen content. The crystal structures of A+ 5‐At– * × H2O (A = Li+ (6), Na+ x = 3 (7), K+ (8), Rb+ (9) and Cs+ (10)) were determined using single crystal X‐ray diffraction and a detailed description is given in this work. In addition the compounds were characterized using vibrational (IR and Raman) and NMR spectroscopy, elemental analysis and differential scanning calorimetry (DSC). Since tetrazoles are known to be promising energetic materials the heats of formation were calculated using bomb calorimetric measurements and the sensitivities of all compounds were tested using BAM methods. They show no sensitivity towards friction (< 360 N) or impact (< 50 J). X‐ray determinations: 6: monoclinic, P21/c, a = 4.7900(5) Å, b = 10.6139(11) Å, c = 7.0369(8) Å, β = 103.260(9)°, V = 348.22(7) Å3, Z = 4; 7: triclinic, $P{\bar 1}$, a = 5.8689(7) Å, b = 10.0258(9) Å, c = 12.1710(12) Å, α = 87.335(11)°, β = 77.546(9)°, γ = 80.059(9)°, V = 688.76(13) Å3, Z = 4; 8: monoclinic, P21/c, a = 9.8516(9) Å, b = 6.8702(8) Å, c = 6.8372(7) Å, β = 115.613(11)°, V = 417.29(8) Å3, Z = 4; 9: orthorhombic, Pnma, a = 7.4221(9) Å, b = 6.8053(8) Å, c = 9.0133(9) Å, V = 455.26(9) Å3, Z = 4; 10: orthorhombic, Pnma, a = 8.0538(7) Å, b = 6.9305(6) Å, c = 9.1021(8) Å, V = 508.05Å3, Z = 4.
Zwei Nitridchloride des Wolframs: W2NCl8 und W2NCl9
Authors: Weisser Martina , Tragl Sonja , Meyer H.‐Jürgen 
Published: April 2007

AbstractTwo Tungsten Nitride Chlorides: W2NCl8 and W2NCl9A solid state reaction of tungsten(VI)chloride and cyanamide yielded black crystals of W2NCl8 and red plate‐like crystals of W2NCl9. The structures of these compounds were determined by single crystal X‐ray diffraction. The crystal structure of W2NCl8 contains [Cl2/2Cl3WNWCl3Cl2/2]‐units forming chains along the c‐axis. The tungsten atoms are linked by a symmetric nitrido bridge (d(W–N) = 1.8203(4) Å). The crystal structure of W2NCl9 contains a dichloro‐bridged dimer of a nitride‐bridged ditungsten unit [Cl5WNWCl3Cl2/2]2 with two different W–N distances of 1.726(9) Å and 2.012(9) Å.
Silver(I) Complexes of 1,3‐Dialkyl‐4,5‐dimethylimidazol‐2‐ylidenes and their Use as Precursors for the Synthesis of Rhenium(V) NHC Complexes
Authors: Oehlke Elisabeth , Kückmann Theresa , Abram Ulrich 
Published: April 2007

AbstractAg(BF4) reacts with N‐heterocyclic carbenes (NHC) of the type 1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐ylidene (LR, R = Me, Et, i‐Pr) under formation of [Ag(LR)2]+ complexes. [Ag(LEt)2](BF4) and [Ag(Li‐Pr)2](BF4) can be isolated from such procedures as air‐stable solids, while the methyl derivative decomposes rapidly in the reaction mixture. The Ag–carbene bond lengths in [Ag(Li‐Pr)2](BF4) are 2.08(1) Å. This is in accordance with the bonding situation in other Ag NHC complexes and does on its own not allow conclusions to be drawn concerning the bonding order or the reactivity of the compound.Reactions of [Ag(LEt)2](BF4) with common rhenium(V) starting materials such as [ReOCl3(PPh3)2] or (NBu4)[ReOCl4] give the known ReV NHC complex [ReO2(LEt)4]+. This transmetallation reaction represents a new approach to rhenium or technetium NHC complexes which possess potential for applications in nuclear medicine.
Organometallic Compounds of the Lanthanides. 181 Alkyllanthanide Carbene Complexes
Authors: Schumann Herbert , Freckmann Dominique M. M. , Schutte Stefan , Dechert Sebastian , Hummert Markus 
Published: April 2007

AbstractLn(CH2SiMe3)3(THF)2 react with 1,3‐di‐iso‐propyl‐4,5‐dimethylimidazol‐2‐ylidene (ImMe2iPr2) yielding Ln(CH2SiMe3)3(THF)(ImMe2iPr2) (1, Ln = Er and 2, Ln = Lu). Reaction of 1 and 2 with an excess of ImMe2iPr2 results in the formation of the heteroleptic alkyllanthanide complexes Ln(CH2SiMe3)3(ImMe2iPr2)2 (3, Ln = Er) and (4, Ln = Lu). The molecular structures of 1, 2, and 4 show a distorded trigonal bipyramidal arrangement around the lanthanide centers with two alkyl ligands and one carbene in the equatorial positions.
Polyol Metal Complexes. Part 54 Multiply Deprotonated Purine Nucleosides as Ligands in Bismutates and Antimonates
Authors: Klüfers Peter , Mayer Peter 
Published: April 2007

AbstractThe crystal structures of [Co(NH3)6][Bi(Guo1,2′,3′H−3)2] · 9 H2O (1), Na[Sb(Ado2′,3′H−2)2] · H2O (2), and Na2[Bi(Ado2′,3′H−2)(Ado2′,3′,5′H−3)] · 13.5 H2O (3) were determined from single‐crystal X‐ray diffraction data (Guo = guanosine, Ado = Adenosine). The chelate complex anions of all structures consist of a bismuth(III) or antimony(III) center which is coordinated by the 1,2‐diolato group of the ribofuranosyl moiety of the nucleosides. In 1, two guanine moieties belonging to different complexes are linked by two hydrogen bonds of the type N2–H···N3. 13C NMR data obtained from the mother liquors show a coordination‐induced shift for the coordinating alkoxido groups of guanosine and adenosine as well as inosine.
Polyol Metal Complexes. Part 55 Germanes with Alkylenedioxy Substituents
Authors: Klüfers Peter , Vogler Constance 
Published: April 2007

AbstractWithin this work five novel germanes with alkylenedioxy substituents derived from 1,2‐diols have been synthesized and structurally characterized. Various coordination patterns from tetra‐ to hexacoordination were determined. Both open‐chain and cyclic 1,2‐diols such as 1,2‐ethandiol (Ethd), 1,1′‐bicyclohexyl‐1,1′‐diol (Bhxd), cis‐oxolane‐3,4‐diol (AnEryt) and cis‐1,2‐cyclopentanediol (cis‐1,2‐Cptd) were used. Tetracoordination of the germanium atom in the crystalline state appears to be restricted to sterically demanding substituents.In general, the tendency of germanium to extend its coordination sphere to build penta‐ or hexacoordinate compounds is demonstrated. It is also shown that germanium is able to compensate a lack of substituents by the formation of dimeric structures.
Laparoscopic Nissen‐Rossetti Fundoplication with Routine Use of Intraoperative Endoscopy and Manometry: Technical Aspects of a Standardized Technique
Authors: del Genio Gianmattia , Rossetti Gianluca , Brusciano Luigi , Limongelli Paolo , Pizza Francesco , Tolone Salvatore , Fei Landino , Maffettone Vincenzo , Napolitano Vincenzo , del Genio Alberto 
Published: April 2007

AbstractBackgroundSeveral different ways of fashioning a total fundoplication lead to different outcomes. This article addresses the technical details of the antireflux technique we adopted without modifications for all patients with GERD beginning in 1972. In particular it aims to discuss the relation between the mechanism of function of the wrap and the physiology of the esophagus.MethodsThe study population consisted of 380 patients affected by GERD with a 1‐year minimum of follow‐up who underwent laparoscopic Nissen‐Rossetti fundoplication by a single surgeon.ResultsNo conversion to open surgery and no mortality occurred. Major complications occurred in 4 patients (1.1%). Follow‐up (median 83 months; range: 1–13 years) was achieved in 96% of the patients. Ninety‐two percent of the patients were satisfied with the results of the procedure and would undergo the same operation again. Postoperative dysphagia occurred in 3.5% of the patients, and recurrent heartburn was observed in 3.8%.ConclusionsLaparoscopic Nissen‐Rossetti fundoplication with the routine use of intraoperative manometry and endoscopy achieved good outcomes and long‐term patient satisfaction with few complications and side‐effects. Appropriate preoperative investigation and a correct surgical technique are important in securing these results.
Recurrence Pattern of Squamous Cell Carcinoma in the Middle Thoracic Esophagus after Modified Ivor‐Lewis Esophagectomy
Authors: Chen Gang , Wang Zhou , Liu Xiang‐yan , Liu Fan‐ying 
Published: April 2007

AbstractBackgroundDespite increasingly radical surgery for esophageal carcinoma, many patients still develop tumor recurrence after operation. This study was designed to evaluate the recurrence pattern of squamous cell carcinoma in the middle thoracic esophagus after modified Ivor‐Lewis esophagectomy.MethodsWe retrospectively reviewed data of 196 patients who underwent modified Ivor‐Lewis esophagectomy with two‐field lymph node dissection from January 1997 to January 2001. Recurrence was classified as locoregional or hematogenous recurrence. Logistic regression analysis was performed to identify risk factors of postoperative recurrence.ResultsThe overall 3‐year and 5‐year survival rates in all patients were 53% and 31%, respectively. Recurrence was recognized in 96 patients (48.9%) in the 3 years after operation. The median time to tumor recurrence was 12.2 months. The pattern of recurrence was locoregional in 52 patients (mainly mediastinal in 41, single cervical/supraclavicular in 8), hematogenous in 44 patients (simultaneous locoregional and hematogenous in 10; mainly liver, bone, or lung in 39). The locoregional recurrence rate was significantly lower in patients with postoperative radiotherapy than that in patients without postoperative radiotherapy (p = 0.02). Logistic regression analysis showed that T3 (p = 0.032), N1 (p = 0.003), and postoperative radiotherapy (p = 0.022) were independent risk factors for tumor locoregional recurrence.ConclusionsAbout one half of the patients would develop recurrent disease within 3 years after modified Ivor‐Lewis esophagectomy with two‐field lymph node dissection, and most of them had mediastinal lymph node, liver, bone, or lung metastasis. Postoperative radiotherapy was beneficial in the control of locoregional recurrence.
Coagulopathy: Its Pathophysiology and Treatment in the Injured Patient
Authors: Tieu Brandon H. , Holcomb John B. , Schreiber Martin A. 
Published: April 2007

AbstractHemorrhage continues to be one of the leading causes of death following trauma. Trauma patients are susceptible to the early development of coagulopathy and the most severely injured patients are coagulopathic on hospital admission. Hypothermia, acidosis, and dilution from standard resuscitation can worsen the presenting coagulopathy and perpetuate bleeding. Early identification of coagulopathy is dependent on clinical awareness and point of care laboratory values. Routinely used laboratory coagulation parameters fail to adequately describe this state. Thrombelastography is a test that can be done at the bedside and uses whole blood to provide a functional evaluation of coagulation. Rapid diagnosis of coagulopathy, followed by prevention or correction of hypothermia and acidosis should be a priority during the initial evaluation and resuscitation. Judicious use of resuscitation fluids and early replacement of coagulation factors will help prevent iatrogenic hemodilution. This review covers the pathophysiology as well as the clinical and laboratory diagnosis of coagulopathy. Prevention and treatment strategies are discussed, including early transfusion of coagulation factors during massive transfusion and the use of recombinant factor VIIa. Damage control resuscitation is briefly discussed, and it involves the combination of hypotensive resuscitation and hemostatic resuscitation. Finally, a description of the use of fresh whole blood in the military setting is included. Its use has been proven to be safe and beneficial in this setting and warrants further investigation as an adjunct to the management of civilian trauma patients.
Intrathyroidal Differentiated Thyroid Carcinoma: Tumor Size‐Based Surgical Concepts
Authors: Miccoli Paolo , Minuto Michele N. , Ugolini Clara , Panicucci Erica , Berti Piero , Massi Marco , Basolo Fulvio 
Published: April 2007

AbstractIntroductionTotal thyroidectomy (TT) remains the treatment of choice for differentiated thyroid carcinomas (DTCs), but a limited approach can be proposed when tumors are at an early stage and limited to a single lobe. The aim of this study was to analyze the pathologic and clinical aspects of a retrospective series of DTCs in an attempt to determine whether these features might prove useful for limiting the surgical strategy in selected cases.MethodsFrom 2000 to 2005, a total of 2798 patients (637 males, 2161 females; mean age 44.6 years) underwent TT for papillary thyroid carcinoma in our department. The histologic features considered were size, histologic subtype and capsule of the tumor, its multifocality/bilaterality, infiltration of the thyroid capsule, and the presence of nodal metastases.ResultsStatistical analysis revealed that among tumors ≤ 1 cm the presence of the tumor capsule, infiltration of the thyroid capsule, bilaterality, and the presence of node metastases were all significantly lower when the tumor size was ≤ 0.5 cm (p < 0.0001). Furthermore, patients with bilateral carcinomas demonstrated a significantly higher presence of a tumor capsule (p = 0.012), infiltration of the thyroid capsule (p < 0.0001), and node metastases (p < 0.0001) and a higher incidence of the “tall‐cells” variant (p < 0.0001) when compared to the unilateral population.ConclusionsBased on these data it is suggested that tumors ≤ 1 cm cannot be considered a homogeneous class of DTCs. Nevertheless, in tumors ≤ 0.5 cm the absence of a “tall‐cells” variant and the absence of infiltration of the thyroid capsule might be useful for avoiding an unnecessary completion thyroidectomy after lobectomy.
Evidence‐based Approach to the Management of Sporadic Medullary Thyroid Carcinoma
Authors: Moley Jeffrey F. , Fialkowski Elizabeth A. 
Published: April 2007

AbstractMedullary thyroid carcinoma (MTC) is a rare malignancy of the thyroid C cells. It occurs in hereditary (25% of cases) and sporadic (75%) forms. Sporadic MTCs frequently metastasize to cervical lymph nodes. Thorough surgical extirpation of the primary tumor and nodal metastases by compartment‐oriented resection has been the mainstay of treatment (level IV evidence). Surgical resection of residual and recurrent disease is effective in reducing calcitonin levels and controlling complications of central neck disease (level IV evidence). Radioactive iodine, external beam radiation therapy, and conventional chemotherapy have not been effective. Newer systemic treatments, with agents that target abnormal RET proteins hold promise and are being tested in clinical trials for patients with metastatic disease.