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LV11429B - Tricyclopolyazamacrocyclophosphonic acids, complexes and derivates thereof, for use as contrast agents - Google Patents

Tricyclopolyazamacrocyclophosphonic acids, complexes and derivates thereof, for use as contrast agents Download PDF

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Publication number
LV11429B
LV11429B LVP-95-361A LV950361A LV11429B LV 11429 B LV11429 B LV 11429B LV 950361 A LV950361 A LV 950361A LV 11429 B LV11429 B LV 11429B
Authority
LV
Latvia
Prior art keywords
formula
compound
alkyl
complex
pharmaceutically acceptable
Prior art date
Application number
LVP-95-361A
Other languages
English (en)
Latvian (lv)
Other versions
LV11429A (lv
Inventor
Garry E Kiefer
Original Assignee
Dow Chemical Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dow Chemical Co filed Critical Dow Chemical Co
Publication of LV11429A publication Critical patent/LV11429A/xx
Publication of LV11429B publication Critical patent/LV11429B/en

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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D471/00Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
    • C07D471/12Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains three hetero rings
    • C07D471/18Bridged systems
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D471/00Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
    • C07D471/22Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed systems contains four or more hetero rings
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02Phosphorus compounds
    • C07F9/547Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
    • C07F9/6561Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom containing systems of two or more relevant hetero rings condensed among themselves or condensed with a common carbocyclic ring or ring system, with or without other non-condensed hetero rings
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/281Means for the use of in vitro contrast agents

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
  • Nitrogen Condensed Heterocyclic Rings (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Luminescent Compositions (AREA)
LVP-95-361A 1993-05-06 1995-12-06 Tricyclopolyazamacrocyclophosphonic acids, complexes and derivates thereof, for use as contrast agents LV11429B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/058,622 US5385893A (en) 1993-05-06 1993-05-06 Tricyclopolyazamacrocyclophosphonic acids, complexes and derivatives thereof, for use as contrast agents
PCT/US1994/005071 WO1994026276A1 (en) 1993-05-06 1994-05-06 Tricyclopolyazamacrocyclophosphonic acids, complexes and derivatives thereof, for use as contrast agents

Publications (2)

Publication Number Publication Date
LV11429A LV11429A (lv) 1996-08-20
LV11429B true LV11429B (en) 1997-04-20

Family

ID=22017946

Family Applications (1)

Application Number Title Priority Date Filing Date
LVP-95-361A LV11429B (en) 1993-05-06 1995-12-06 Tricyclopolyazamacrocyclophosphonic acids, complexes and derivates thereof, for use as contrast agents

Country Status (17)

Country Link
US (1) US5385893A (de)
EP (1) EP0697872B1 (de)
JP (1) JP3553940B2 (de)
KR (1) KR960702462A (de)
CN (1) CN1125906A (de)
AT (1) ATE316377T1 (de)
AU (1) AU687400B2 (de)
BG (1) BG100194A (de)
CA (1) CA2162172A1 (de)
DE (1) DE69434618T2 (de)
FI (1) FI955336A (de)
HU (1) HUT72649A (de)
LV (1) LV11429B (de)
NO (1) NO954441L (de)
PL (1) PL311649A1 (de)
SG (1) SG46496A1 (de)
WO (1) WO1994026276A1 (de)

Families Citing this family (72)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5645818A (en) * 1989-03-24 1997-07-08 Guerbet S.A. Diagnostic compositions comprising a complex formed by a nitrogenous macrocyclic ligand with metal ions
US5739294A (en) * 1991-12-10 1998-04-14 The Dow Chemical Company Bicyclopol yazamacrocyclophosphonic acid complexes for use as contrast agents
US5714604A (en) * 1993-05-06 1998-02-03 The Dow Chemical Company Process for the preparation of azamacrocyclic or acyclic aminophosphonate ester derivatives
US5672335A (en) * 1994-11-30 1997-09-30 Schering Aktiengesellschaft Use of metal complexes as liver and gallbladder X-ray diagnostic agents
US6207826B1 (en) * 1995-03-27 2001-03-27 Isis Pharmaceuticals, Inc. Macrocyclic compounds having nitrogen-containing linkages
US6107482A (en) * 1995-03-27 2000-08-22 Isis Pharmaceuticals, Inc. Nitrogenous macrocyclic compounds
DE19546234C1 (de) * 1995-12-04 1997-08-28 Schering Ag Neue makrobicyclische Verbindungen, Verfahren zu ihrer Herstellung und diese makrobicyclischen Verbindungen enthaltende pharmazeutische Mittel
US5834456A (en) * 1996-02-23 1998-11-10 The Dow Chemical Company Polyazamacrocyclofluoromonoalkylphosphonic acids, and their complexes, for use as contrast agents
CA2251924C (en) * 1996-04-19 2006-05-30 The Dow Chemical Company Fluorescent chelates as visual tissue specific imaging agents
DE69906732T2 (de) * 1998-06-15 2003-10-16 Unilever N.V., Rotterdam Bleichkatalysatoren und sie enthaltende formulierungen
AU1092601A (en) * 1999-10-18 2001-04-30 Dow Global Technologies Inc. Aminoalkylenephosphonates for treatment of bone disorders
US6794371B1 (en) * 1999-10-18 2004-09-21 The Dow Chemical Company Aminoalkylenephosphonates for treatment of bone disorders
EP1778699A4 (de) * 2004-08-10 2009-02-25 Dow Global Technologies Inc Targeting von chelanten und chelaten
US20100111856A1 (en) 2004-09-23 2010-05-06 Herman Gill Zirconium-radiolabeled, cysteine engineered antibody conjugates
KR101270829B1 (ko) 2004-09-23 2013-06-07 제넨테크, 인크. 시스테인 유전자조작 항체 및 접합체
MX2008015132A (es) 2006-05-30 2008-12-10 Genentech Inc Anticuerpos e inmunoconjugados y sus usos.
PL2845866T3 (pl) 2006-10-27 2017-10-31 Genentech Inc Przeciwciała i immunokoniugaty oraz ich zastosowanie
WO2008100805A2 (en) 2007-02-09 2008-08-21 Genentech, Inc. Anti-robo4 antibodies and uses therefor
PL2474557T3 (pl) 2007-07-16 2015-02-27 Genentech Inc Przeciwciała anty- CD79b i immunokoniugaty i sposoby stosowania
KR101559595B1 (ko) 2007-07-16 2015-10-12 제넨테크, 인크. 인간화 항-cd79b 항체 및 면역접합체 및 사용 방법
IL295449A (en) 2008-01-31 2022-10-01 Genentech Inc and fusion antibody-drug-cd79b engineered antibodies cysteine-
JP6132548B2 (ja) 2009-04-01 2017-05-24 ジェネンテック, インコーポレイテッド 抗FcRH5抗体および免疫接合体および使用方法
AU2010256410B2 (en) 2009-06-04 2016-10-20 Massachusetts Institute Of Technology Methods for identification of sites for IgG conjugation
CN102510774B (zh) * 2009-09-18 2014-07-23 科莱恩金融(Bvi)有限公司 制备桥联的三氮杂环壬烷的锰络合物的方法
RU2580038C2 (ru) 2009-12-04 2016-04-10 Дженентек, Инк. Мультиспецифические антитела, аналоги антител, композиции и способы
MX336109B (es) 2010-06-03 2016-01-08 Genentech Inc Formacion de imagenes inmuno-tep de anticuerpos e inmunoconjugados y usos de lo mismo.
RU2755066C2 (ru) 2010-06-08 2021-09-13 Дженентек, Инк. Полученные с помощью генной инженерии антитела с цистеиновыми заменами и их конъюгаты
EP3138580B1 (de) 2012-07-04 2021-03-03 F. Hoffmann-La Roche AG Kovalent verknüpfte antigen-antikörper-konjugate
EP2869837B1 (de) 2012-07-04 2016-09-14 F. Hoffmann-La Roche AG Anti-theophyllin-antikörper und verwendungsverfahren
WO2014006123A1 (en) 2012-07-04 2014-01-09 F. Hoffmann-La Roche Ag Anti-biotin antibodies and methods of use
RU2694981C2 (ru) 2014-01-03 2019-07-18 Ф. Хоффманн-Ля Рош Аг Ковалентно связанные конъюгаты хеликар-антитело против хеликара и их применения
WO2015101586A1 (en) 2014-01-03 2015-07-09 F. Hoffmann-La Roche Ag Bispecific anti-hapten/anti-blood brain barrier receptor antibodies, complexes thereof and their use as blood brain barrier shuttles
RU2682754C2 (ru) 2014-01-03 2019-03-21 Ф. Хоффманн-Ля Рош Аг Конъюгаты полипептидного токсина и антитела, соединенных ковалентной связью
EP3191521A2 (de) 2014-09-12 2017-07-19 F. Hoffmann-La Roche AG Cystein-manipulierte antikörper und konjugate
WO2016096741A1 (en) 2014-12-17 2016-06-23 F. Hoffmann-La Roche Ag Novel methods for enzyme mediated polypeptide conjugation using sortase
EP3353310B1 (de) 2015-09-25 2020-04-29 H. Hoffnabb-La Roche Ag Verfahren zur herstellung von thioestern unter verwendung einer sortase a
KR102692686B1 (ko) 2015-09-25 2024-08-06 에프. 호프만-라 로슈 아게 소르타아제 접합 루프를 포함하는 재조합 면역글로불린 중쇄 및 이의 접합체
CN108138158B (zh) 2015-09-25 2021-11-09 豪夫迈·罗氏有限公司 可溶性分选酶a
JP6998863B2 (ja) 2015-09-25 2022-02-04 エフ.ホフマン-ラ ロシュ アーゲー 深共融溶媒におけるソルターゼaを利用したアミド基転移
WO2017089849A1 (en) 2015-11-26 2017-06-01 Debreceni Egyetem New 6-oxa-3,9, 15-triaza-bicyclo[9.3.1 ]pentadec a- 1 ( 14), 1 1 ( 15), 12-triene derivatives based compounds and their application as ligands of essential metal ion based mri and 52mn based pet contrast agents
WO2017089847A1 (en) 2015-11-26 2017-06-01 Debreceni Egyetem New 3,6,9, 15-tetraaza-bicyclo [9.3.1 ]pentadeca- 1(14), 11(15), 12-triene based compounds and their application as ligands of essential metal ion based mri and 52mn based pet contrast agents
EP3380473A1 (de) * 2015-11-26 2018-10-03 Debreceni Egyetem Neue 2,1-l-diaza-[3.3](2,6)pyridinophan-verbindungen und deren anwendung als liganden von auf essentiellen metallionen basierenden mrt-kontrastmitteln und 52mn-basierenden pet-kontrastmitteln
FR3045053B1 (fr) 2015-12-09 2018-01-05 Cisbio Bioassays Agents complexants hydrosolubles a base de triazapyridinophane et complexes de lanthanide fluorescents correspondants
WO2017167712A1 (en) 2016-03-30 2017-10-05 F. Hoffmann-La Roche Ag Improved sortase
KR102495650B1 (ko) 2017-04-12 2023-02-02 에프. 호프만-라 로슈 아게 알데히드 함유 표적 분자의 라벨링 방법
EP3652214A1 (de) 2017-07-13 2020-05-20 H. Hoffnabb-La Roche Ag Neues bindemittel und assay für pivka
CN111212850B (zh) 2017-10-20 2024-04-16 豪夫迈·罗氏有限公司 关于抗体的复制保护
JP7402158B2 (ja) 2017-11-30 2023-12-20 ジェネンテック, インコーポレイテッド 抗pd-l1抗体及びpd-l1を検出するためにそれを使用する方法
JP2021515567A (ja) 2018-03-14 2021-06-24 エフ.ホフマン−ラ ロシュ アーゲーF. Hoffmann−La Roche Aktiengesellschaft 新規抗トロポニンt抗体
WO2019175131A1 (en) 2018-03-14 2019-09-19 F. Hoffmann-La Roche Ag Method for affinity maturation of antibodies
JP2021522192A (ja) 2018-04-18 2021-08-30 エフ.ホフマン−ラ ロシュ アーゲーF. Hoffmann−La Roche Aktiengesellschaft 新規抗チミジンキナーゼ抗体
JP7577647B2 (ja) 2018-08-31 2024-11-05 エフ. ホフマン-ラ ロシュ アーゲー Dlbclについての予後指標におけるチミジンキナーゼ(tk-1)
WO2020069433A1 (en) 2018-09-28 2020-04-02 Imaginab, Inc. Cd8 imaging constructs and methods of use thereof
KR20220016210A (ko) 2019-07-22 2022-02-08 에프. 호프만-라 로슈 아게 자궁내막증의 비-침습적 진단용 혈액 생물표지자로써 s100a9
KR20220024782A (ko) 2019-07-22 2022-03-03 에프. 호프만-라 로슈 아게 자궁내막증의 비침습적 진단을 위한 혈액 바이오마커로서의 s100a8
BR112022001140A2 (pt) 2019-07-22 2022-03-15 Hoffmann La Roche Métodos para avaliar se um paciente tem endometriose ou está em risco de desenvolver endometriose, selecionar um paciente para terapia e monitorar um paciente que sofre de endometriose ou que está sendo tratado para endometriose
CN114144674A (zh) 2019-07-22 2022-03-04 豪夫迈·罗氏有限公司 P物质作为用于子宫内膜异位症的非侵入性诊断的血液生物标志物
JP2022542056A (ja) 2019-07-22 2022-09-29 エフ.ホフマン-ラ ロシュ アーゲー 子宮内膜症の非侵襲的診断のための血液バイオマーカーとしてのs100a6
BR112022009371A2 (pt) 2019-11-15 2022-08-09 Hoffmann La Roche Métodos para determinar a quantidade ou concentração de um ou mais analitos antibióticos, tubos de amostragem, usos de um reagente de derivatização nucleofílica e analito antibiótico
CN116457660A (zh) 2020-10-30 2023-07-18 豪夫迈·罗氏有限公司 Timp1作为胆管癌的标志物
EP4237441A1 (de) 2020-11-02 2023-09-06 F. Hoffmann-La Roche AG Sars-cov-2-nukleocapsid-antikörper
WO2022207628A1 (en) 2021-03-30 2022-10-06 F. Hoffmann-La Roche Ag Scf as blood biomarker for the non-invasive diagnosis of endometriosis
EP4314838A1 (de) 2021-04-01 2024-02-07 F. Hoffmann-La Roche AG Psp94 als blutbiomarker zur nichtinvasiven diagnose von endometriose
WO2022243210A1 (en) 2021-05-17 2022-11-24 F. Hoffmann-La Roche Ag sFRP4 AS BLOOD BIOMARKER FOR THE NON-INVASIVE DIAGNOSIS OF ADENOMYOSIS
WO2023072904A1 (en) 2021-10-26 2023-05-04 F. Hoffmann-La Roche Ag Monoclonal antibodies specific for sars-cov-2 rbd
EP4448564A1 (de) 2021-12-17 2024-10-23 F. Hoffmann-La Roche AG Neuer antikörper zum nachweis von amyloid beta 42 (a-beta42)
WO2023131594A1 (en) 2022-01-05 2023-07-13 F. Hoffmann-La Roche Ag Derivatization of compounds in patient samples for therapeutic drug monitoring (tdm)
WO2023247752A1 (en) 2022-06-23 2023-12-28 F. Hoffmann-La Roche Ag Method for diagnosing endometriosis and for classifying the stage of endometriosis
WO2024017983A1 (en) 2022-07-22 2024-01-25 F. Hoffmann-La Roche Ag Meteorin-like protein (metrnl) as (blood) biomarker for the diagnosis of polycystic ovarian syndrome
WO2024017982A1 (en) 2022-07-22 2024-01-25 F. Hoffmann-La Roche Ag Leukotriene a4 hydrolase (lta4h) as (blood) biomarker for the diagnosis of polycystic ovarian syndrome
WO2024017985A1 (en) 2022-07-22 2024-01-25 F. Hoffmann-La Roche Ag Fibroblast growth factor binding protein 1 (fgfbp1) as (blood) biomarker for the diagnosis of polycystic ovarian syndrome
WO2025026908A1 (en) 2023-07-28 2025-02-06 Roche Diagnostics Gmbh Serum epha1 as biomarker for endometriosis

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2609390A (en) * 1950-06-01 1952-09-02 Frederick C Bersworth Phosphonic alkylene polyamino acids and method of producing same
US3336221A (en) * 1964-11-05 1967-08-15 Calgon Corp Method of inhibiting precipitation and scale formation
US3331773A (en) * 1966-07-22 1967-07-18 Grace W R & Co Process for inhibiting precipitation in water
US3434969A (en) * 1967-08-11 1969-03-25 Calgon Corp Scale inhibiting
GB1441081A (en) * 1974-01-09 1976-06-30 Ici Ltd Tetra-aza-macrocycles and their metal complexes
US4980148A (en) * 1985-02-06 1990-12-25 Mallinckrodt, Inc. Methods for enhancing magnetic resonance imaging
US4880008A (en) * 1985-05-08 1989-11-14 The General Hospital Corporation Vivo enhancement of NMR relaxivity
US4899755A (en) * 1985-05-08 1990-02-13 The General Hospital Corporation Hepatobiliary NMR contrast agents
DE3825040A1 (de) * 1988-07-20 1990-01-25 Schering Ag, 13353 Berlin 5- oder 6-ring- enthaltende makrocyclische polyaza-verbindungen, verfahren zu ihrer herstellung und diese enthaltende pharmazeutische mittel
US5247077A (en) * 1989-06-23 1993-09-21 Celltech Limited Tri-aza macrocycles and processes for their preparation
ATE160943T1 (de) * 1991-12-10 1997-12-15 Dow Chemical Co Bicycloazamakrocyclophosphon-säure, komplexe, konjugate, kontrastmittel und herstellung
HU9302308D0 (en) * 1991-12-10 1993-12-28 Dow Chemical Co Process for production lof biciclo-polyaza-macrocyclyc-carbonic acid-complexes and their conjugates and of medical preparatives containing them
US5428139A (en) * 1991-12-10 1995-06-27 The Dow Chemical Company Bicyclopolyazamacrocyclophosphonic acid complexes for use as radiopharmaceuticals
AU3415493A (en) * 1991-12-10 1993-07-19 Dow Chemical Company, The Bicycle-polyazamacrocyclocarboxylic acid complexes, conjugates, preparation and use as contrast agents

Also Published As

Publication number Publication date
LV11429A (lv) 1996-08-20
WO1994026276A1 (en) 1994-11-24
EP0697872A1 (de) 1996-02-28
JPH08511003A (ja) 1996-11-19
US5385893A (en) 1995-01-31
DE69434618D1 (de) 2006-04-13
FI955336A (fi) 1995-12-22
EP0697872B1 (de) 2006-01-25
AU687400B2 (en) 1998-02-26
ATE316377T1 (de) 2006-02-15
KR960702462A (ko) 1996-04-27
NO954441D0 (no) 1995-11-06
CA2162172A1 (en) 1994-11-24
NO954441L (no) 1996-01-05
DE69434618T2 (de) 2006-08-10
BG100194A (en) 1996-12-31
PL311649A1 (en) 1996-03-04
EP0697872A4 (de) 2003-04-02
HUT72649A (en) 1996-05-28
SG46496A1 (en) 1998-02-20
FI955336A0 (fi) 1995-11-06
AU6784994A (en) 1994-12-12
HU9502023D0 (en) 1995-09-28
CN1125906A (zh) 1996-07-03
JP3553940B2 (ja) 2004-08-11

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