bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thiourea Inhibitors of Herpes Viruses. Part 1. Bis‐(aryl)thiourea Inhibitors of CMV.
Authors: Bloom Jonathan D. , DiGrandi Martin J. , Dushin Russel G. , Curran Kevin J. , Ross Adma A. , Norton Emily B. , Terefenko Eugene , Jones Thomas R. , Feld Boris , Lang Stanley A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Reaction of N1,N2‐Diarylamidines with (2,3‐Diphenylcyclopropen‐1‐ylidene)propanedinitrile: Synthesis of [2‐Arylamino‐4(1H)‐pyridinylidene]propanedinitriles.
Authors: Gomaa Mohsen A.‐M. , Doepp Dietrich 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
3‐(1‐Pyrrolyl)thieno[2,3‐b]pyridine — A New Conjugated Heterocyclic System
Authors: Kaigorodova E. A. , Osipova A. A. , Vasilin V. K. , Konyushkin L. D. , Krapivin G. D. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of N‐(Substituted aryl/cyclohexyl)‐N′‐ [5‐bromo‐5‐nitro‐2‐oxido‐1,3,2‐dioxaphosphorinane‐2‐yl]ureas.
Authors: Reddy P. Vasu Govardhana , Babu Y. Hari , Reddy C. Suresh 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Isolation of Peridinin‐Related Norcarotenoids with Cell Growth‐Inhibitory Activity from the Cultured Dinoflagellate of Symbiodinium sp., a Symbiont of the Okinawa Soft Coral Clavularia viridis, and Analysis of Fatty Acids of the Dinoflagellate.
Authors: Suzuki Motoya , Watanabe Kinzo , Fujiwara Shoko , Kurasawa Toshie , Wakabayashi Takako , Tsuzuki Mikio , Iguchi Kazuo , Yamori Takao 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Total Synthesis and Determination of the Absolute Configuration of Rishirilide B: Exploitation of Subtle Effects to Control the Sense of Cycloaddition of o‐Quinodimethides.
Authors: Yamamoto Kana , Hentemann Martin F. , Allen John G. , Danishefsky Samuel J. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Chiral P*‐Monodentate Phosphite Ligand for Pd‐Catalyzed Asymmetric Allylation Reactions.
Authors: Gavrilov Konstantin N. , Tsarev Vasily N. , Lyubimov Sergey E. , Shyryaev Alexei A. , Zheglov Sergey V. , Bondarev Oleg G. , Davankov Vadim A. , Kabro Anzhelika A. , Moiseev Sergey K. , Kalinin Valery N. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Macrocyclic Pyrimidine Derivatives.
Authors: Krivonogov V. P. , Kozlova G. G. , Sivkova G. A. , Spirikhin L. V. , Abdrakhmanov I. B. , Murinov Yu. I. , Tolstikov G. A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A Convenient Method for the Synthesis of β,γ‐Unsaturated Amines from Alkenes via α,β‐Unsaturated Diphenylsulfonium Salts.
Authors: Yamanaka Hiroyuki , Matsuo Jun‐ichi , Kawana Asahi , Mukaiyama Teruaki 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Catalytic Asymmetric Oxidation of Alkyl Aryl Sulfides Mediated by a Series of Chiral N‐Alkyl‐1,2‐diphenylaminoethanol/Titanium/Water Complexes.
Authors: Peng YunGui , Feng XiaoMing , Cui Xin , Jiang YaoZhong , Choi Michael C. K. , Chan Albert S. C. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
[2 + 3] Cycloadditions Between Nitroalkenes and Camphor‐Derived Oxazoline N‐Oxides and Radical Denitration of the Adducts.
Authors: Voituriez Arnaud , Moulinas Julien , Kouklovsky Cyrille , Langlois Yves 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Novel Tricyclic Heterocyclic Compounds as Potential Anticancer Agents Using Chromanone and Thiochromanone as Synthons.
Authors: Hammam Abou El‐Fotooh G. , Fahmy A. F. M. , Amr Abdel‐Galil E. , Mohamed Ashraf M. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Studies on BF3×Et2O‐Catalyzed Cyclization of 2‐Aryl‐1‐(2,4,4‐trimethyl‐1‐cyclohexen‐3‐yl)‐ethanone.
Authors: Bie Pingyan , Zhang Chenglu , Peng Xuanjia , Chen Bo , Wu Tongxing , Pan Xinfu 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Thermophysical Properties of BaZrO3 and BaCeO3.
Authors: Yamanaka Shinsuke , Fujikane Masaki , Hamaguchi Tsuyoshi , Muta Hiroaki , Oyama Taku , Matsuda Tetsushi , Kobayashi Shin‐ichi , Kurosaki Ken 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
BINAP/AgOTf/KF/18‐Crown‐6 as New Bifunctional Catalysts for Asymmetric Sakurai—Hosomi Allylation and Mukaiyama Aldol Reaction.
Authors: Wadamoto Manabu , Ozasa Nobuko , Yanagisawa Akira , Yamamoto Hisashi 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
“Syn‐Effect” in the Conversion of (E)‐α,β‐Unsaturated Esters to the Corresponding β,γ‐Unsaturated Esters.
Authors: Guha Samar Kumar , Shibayama Atsushi , Abe Daisuke , Ukaji Yutaka , Inomata Katsuhiko 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Structure of Benzimidazo[1,2‐c][1,2,3]thiadiazoles: First Examples of a Novel Ring System.
Authors: Tumkevicius Sigitas , Labanauskas Linas , Bucinskaite Virginija , Brukstus Algirdas , Urbelis Gintaras 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Ruthenium Olefin Metathesis Catalysts with Modified Styrene Ethers: Influence of Steric and Electronic Effects.
Authors: Zaja Mirko , Connon Stephen J. , Dunne Aideen M. , Rivard Michael , Buschmann Nicole , Jiricek Jan , Blechert Siegfried 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Efficient Synthesis of Sterically Constrained Symmetrically α,α‐Disubstituted α‐Amino Acids under Operationally Convenient Conditions.
Authors: Ellis Trevor K. , Martin Collin H. , Tsai Gary M. , Ueki Hisanori , Soloshonok Vadim A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A Simple Synthesis of B‐2‐(1‐Trimethylsilyl‐1‐alkyl)‐1,3,2‐dioxaborinanes. Isolation and Selective Oxidation to 1‐Trimethylsilyl‐1‐alkanols.
Authors: Bhat Narayan G. , Garza Amanda 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Alkaline Metal Stannide‐Stannates: “Double Salts” with Zintl Sn4‐4 and Stannate SnO4‐3 Anions.
Authors: Frisch Gero , Hoch Constantin , Roehr Caroline , Zoennchen Peter , Becker Klaus‐Dieter , Niemeier Dirk 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Magnesium Hydrogensulfate: A Cheap and Efficient Catalyst for the Conversion of Epoxides into β‐Alkoxy Alcohols, Vicinal‐Diols, and Thiiranes.
Authors: Salehi Peyman , Khodaei Mohammad Mahdi , Zolfigol Mohammad Ali , Keyvan Afsaneh 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Bridgedhead Azolo[3,2‐a]pyrimidines and Imidazo[2,1‐b]thiazines Through Ring Transformation of 2H‐Pyran‐2‐ones.
Authors: Ram Vishnu Ji , Srivastava Pratibha , Goel Atul 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Acetonyltriphenylphosphonium Bromide and Its Polymer‐Supported Analogues as Catalysts for the Protection of Carbonyl Compounds as Acetals or Thioacetals.
Authors: Hon Yung‐Son , Lee Chia‐Fu , Chen Rong‐Jiunn , Huang Yi‐Fen 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Novel (Phenylalkyl)amines for the Investigation of Structure—Activity Relationships. Part 3. 4‐Ethynyl‐2,5‐dimethoxyphenethylamine (= 4‐Ethynyl‐2,5‐dimethoxybenzeneethanamine; 2C‐YN).
Authors: Trachsel Daniel 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A Practical Oxone®‐Mediated, High‐Throughput, Solution‐Phase Synthesis of Benzimidazoles from 1,2‐Phenylenediamines and Aldehydes and Its Application to Preparative Scale Synthesis.
Authors: Beaulieu Pierre L. , Hache Bruno , von Moos Elisabeth 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Hypocholesterolemic Activity of Hesperetin Derivatives.
Authors: Jeong Tae‐Sook , Kim Eun Eai , Lee Chul‐Ho , Oh Jung‐Hoon , Moon Surk‐Sik , Lee Woo Song , Oh Goo‐Taeg , Lee Sangku , Bok Song‐Hae 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Heck‐Mediated Synthesis and Photochemically Induced Cyclization of [2‐(2‐Styrylphenyl)ethyl]carbamic Acid Ethyl Esters and 2‐Styryl‐benzoic Acid Methyl Esters: Total Synthesis of Naphtho[2,1‐f]isoquinolines (2‐Azachrysenes).
Authors: Pampin M. Carme , Estevez Juan C. , Estevez Ramon J. , Maestro Miguel , Castedo Luis 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
An Alternative Approach Towards Novel Heterocycle‐Fused 1,4‐Diazepin‐2‐ones by an Aromatic Amidation Protocol.
Authors: Correa Arkaitz , Herrero M. Teresa , Tellitu Imanol , Dominguez Esther , Moreno Isabel , SanMartin Raul 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Chiral Discrimination of Aromatic Amino Acids by Capillary Electrophoresis in (+)‐ and (‐)‐(18‐Crown‐6)‐2,3,11,12‐tetracarboxylic Acid Selector Modes.
Authors: Lee Wonjae , La Sookie , Choi Youngmie , Kim Kyoung‐Rae 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Design, Synthesis and Evaluation of Novel Azasugar‐Based MMP/ADAM Inhibitors.
Authors: Moriyama Hideki , Tsukida Takahiro , Inoue Yoshimasa , Kondo Hirosato , Yoshino Kohichiro , Nishimura Shin‐Ichiro 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Enzymatic Synthesis of Nucleoside‐5′‐O‐(1‐thiophosphates) and (SP)‐Adenosine‐5′‐O‐(1‐thiotriphosphate).
Authors: Barai Vladimir N. , Zinchenko Anatoli I. , Kvach Sergei V. , Titovich Olga I. , Rubinova Elena B. , Kalinichenko Elena N. , Mikhailopulo Igor A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Novel 3‐O‐Acyl Mesquitol Analogues as Free‐Radical Scavengers and Enzyme Inhibitors: Synthesis, Biological Evaluation and Structure—Activity Relationship.
Authors: Rao R. Jagadeeshwar , Tiwari Ashok K. , Kumar U. Sampath , Reddy S. Venkat , Ali Amtul Z. , Rao J. Madhusudana 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Highly Enantioselective Construction of Quaternary Stereocenters on β‐Keto Esters by Phase‐Transfer Catalytic Asymmetric Alkylation and Michael Reaction.
Authors: Ooi Takashi , Miki Takashi , Taniguchi Mika , Shirashi Misato , Takeuchi Mifune , Maruoka Keiji 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Sonogashira Coupling Using Bulky Palladium‐Phenanthryl Imidazolium Carbene Catalysis.
Authors: Ma Yudao , Song Chun , Jiang Wei , Wu Quansheng , Wang Yong , Liu Xueying , Andrus Merritt B. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Hydrothermal Synthesis in the System Ni(OH)2—NiSO4: Nuclear and Magnetic Structures and Magnetic Properties of Ni3(OH)2(SO4)2 (H2O)2.
Authors: Vilminot Serge , Richard‐Plouet Mireille , Andre Gilles , Swierczynski Dariusz , Bouree‐Vigneron Francoise , Kurmoo Mohamedally 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Enantioselective Michael Additions of β‐Keto Esters to α,β‐Unsaturated Carbonyl Compounds Catalyzed by a Chiral Biquinoline N,N′‐Dioxide‐Scandium Trifluoromethanesulfonate Complex.
Authors: Nakajima Makoto , Yamamoto Satoshi , Yamaguchi Yukiko , Nakamura Seiichi , Hashimoto Shunichi 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
N‐Bromosuccinimide and Iodine‐Catalyzed Highly Efficient Deoxygenation of Sulfoxides to Thioethers Using 3‐Mercaptopropionic Acid under Mild Reaction Conditions.
Authors: Karimi Babak , Zareyee Daryoush 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Highly Substituted 1,3‐Dienes and 1,3,5‐Trienes by the Palladium‐Catalyzed Coupling of Vinylic Halides, Internal Alkynes, and Organoboranes.
Authors: Zhang Xiaoxia , Larock Richard C. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Antiviral Activity of 4,6‐Di‐tert‐butyl‐2‐aminophenol Derivatives.
Authors: Shadyro O. I. , Sorokin V. L. , Ksendzova G. A. , Polozov G. I. , Nikolaeva S. N. , Pavlova N. I. , Savinova O. V. , Boreko E. I. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
An Efficient Total Synthesis of 9‐Methoxycarbazole‐3‐carbaldehyde Based on a Novel Methodology for the Preparation of Methoxyindoles.
Authors: Selvakumar N. , Khera Manoj Kumar , Reddy B. Yadi , Srinivas D. , Azhagan A. Malar , Iqbal Javed 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A Practical Synthesis of Enantiopure (S)‐4‐(4‐Hydroxybenzyl)‐oxazolidin‐2‐one.
Authors: Green Rachel , Taylor Piers J. M. , Bull Steven D. , James Tony D. , Mahon Mary F. , Merritt Andy T. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
One‐Pot Hydroformylation/Intramolecular Aldol Condensation Reactions of 1‐Allyl‐2‐carbonylpyrroles: A New Entry into Hydroindolizines Synthesis.
Authors: Settambolo Roberta , Miniati Sandra , Lazzaroni Raffaello 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Novel Syntheses of 5‐Aminothieno[2,3‐c]pyridazine, Pyrimido[4′,5′:4,5]thieno[2,3‐c]pyridazine, Pyridazino[4′,3′:4,5]thieno[3,2‐d][1,2,3]triazine and Phthalazine Derivatives.
Authors: El‐Gaby Mohamed S. A. , El‐Dean Abdel M. Kamal , Gaber Abd El‐Aal M. , Eyada Hassan A. , Al‐Kamali Ahmed S. N. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Purines, Pyrimidines, and Related Fused Systems. Part 20. Heterocyclizations of 6‐Alkynyl‐1,3‐dimethyllumazines. Synthesis of Pyrrole and Thiophene Analogues of Some Natural Pteridines.
Authors: Gulevskaya A. V. , Van Shee Dang , Pozharskii A. F. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Macrocyclic Compounds Containing Three Pyrimidine Fragments
Authors: Mikhailov A. S. , Giniyatullin R. Kh. , Semenov V. E. , Reznik V. S. , Nafikova A. A. , Latypov Sh. K. , Efremov Yu. Ya. , Sharafutdinova D. R. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
(1S,2R/1R,2S)‐Aminocyclohexyl Glycyl Thymine PNA: Synthesis, Monomer Crystal Structures, and DNA/RNA Hybridization Studies.
Authors: Govindaraju T. , Gonnade Rajesh G. , Bhadbhade Mohan M. , Kumar Vaijayanti A. , Ganesh Krishna N. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Structure and Properties of New Ionic Liquids Based on Alkyl‐ and Alkenyltrifluoroborates
Authors: Zhou Zhi‐Bin , Matsumoto Hajime , Tatsumi Kuniaki 
Published: July 2005

AbstractA new series of low‐melting, low‐viscosity, hydrophilic ionic liquids, which comprise 1‐ethyl‐3‐methylimidazolium ([EMI]+) and alkyl(alkenyl)trifluoroborate anions ([RBF3]−, R=n‐CmH2m+1 (m=1–5), CH2CH), were prepared and characterized. The phase‐transition behavior, thermal stability, density, viscosity, conductivity, and surface tension of these salts were measured. The influence of the structural variations, such as changing the length and fluorination of the alkyl chain (R) in the anion [RBF3]−, on the above properties was extensively investigated. The low viscosity of these [RBF3]− salts suggests that a high degree of freedom and/or a somewhat flat‐shaped feature in the anion make an important contribution to reducing the viscosity. The Walden products for each salt are not constant and vary with temperature, which suggests that the ions in these salts are not completely dissociated.
Comparative flow cytometric analysis of proliferating cell nuclear antigen (PCNA) antibodies in human solid neoplasms
Authors: Teague Kim , El‐Naggar Adel 
Published: June 2005

AbstractProliferating cell nuclear antigen (PCNA), an auxiliary protein of DNA polymerise δ, associated with DNA synthesis, is increasingly used to determine tumor growth rate. To determine the growth fraction by PCNA, various antibodies and fixation procedures are being used. We assessed the flow‐cytametric measurement of PCNA using three monoclonal antibodies (PC 10, 19F4, and 19A2) and two fixation protocols (paraformaldehyde and methanol) in tissue‐culture cell lines and human solid neoplasms to determine their potential clinical application. Thirty‐one solid tumors and four normal tissues were analyzed, along with MOLT‐4 and HL‐60 cell lines as positive controls and normal peripheral blood lymphocytes as a negative control. PC 10 with methanol, fixation consistently detected higher PCNA positivity in human solid neoplasms than 19F4 and 19A2. Using PC10, the differences in positivity among fixation methods occurred in the G0/1 phase, not in S+G2M, of the cell cycle. No correlation was found between PCNA positivity and tumor grade and DNA ploidy in tumors analyzed. A statistical correlation was found between overall PCNA positivity and RNA content as determined by acridine orange analysis. The growth fraction by PCNA in solid neoplasms was most reliably determined by PC 10 with methanol fixation. © 1994 Wiley‐Liss, Inc.
Single UV excitation of hoechst 33342 and ethidium bromide for simultaneous cell cycle analysis and viability determinations on in vitro cultures of murine B lymphocytes
Authors: Boltz R. C.“Dutch” , Fischer Paul A. , Wicker Linda S. , Peterson Laurence B. 
Published: June 2005

AbstractAssessment of DNA content by flow cytometry has largely depended on staining techniques which do not permit exclusion of dead cells from the data set. During studies of B cell activation in vitro, the large number of nonviable cells greatly affects the cell cycle distribution and thus the accurate evaluation of proliferation flow cytometry. This report describes the development of two dual staining techniques which use Hoechst 33342 and ethidium bromide excited by a single UV source to eliminate dead cells from the DNA histogram of the viable cells in murine B cell cultures. Hoechst 33342 and 0. 62 μg/ml of ethidium bromide permit the evaluation of cell cycle distributions on the viable cells with a ratio gate. The combination of Hoechst 33342 and 6.2 μg/ml ethidium bromide results in the resolution of the two populations due to fluorescence energy transfer with a single PMT. Using this technique we demonstrated the simultaneous determination of DNA and RNA content on viable cells using only two PMTs. Both these techniques can be performed on either a laser or an arc lamp flow cytometer where CVs of less than 7% and as low as 3.2% are normally achieved. Determination of the S phase using these techniques produces a high correlation with DNA synthesis determined by radiolabeled precursor determination. These techniques permit the use of flow cytometry to determine proliferation during B cell activation. © 1994 Wiley‐Liss, Inc.
Flow cytometric study of the type II pneumocyte cell cycle in vivo and in vitro
Authors: Uhal Bruce D. 
Published: June 2005

AbstractThe type II pneumocyte cell cycle was studied in vivo and in vitro through bivariate flow cytometric analysis of DNA content vs. incorporated 5–bromo‐2–deoxyuridine (BrdUrd). The cell cycle phase durations, Ts (7. 8 h) and TG2/M (1.1 h), measured in vivo, agreed well with earlier estimates obtained by thymidine labeling. Left unilateral pneumonectomy increased the BrdUrd labeling index of type II cells in the remaining lung from an initial value of 1.9 ± 0. 3% to 4.8 ± 1.0%, but had no effect on Ts or TG2/M in vivo. In both normal and pneumonectomized animals, BrdUrd‐positive cells in vivo rapidly completed mitosis but did not enter a second S‐phase. These results demonstrate that proliferating type II cells do not form a continuously cycling population in the normal or regenerating adult lung. When cell cycle parameters were measured in vitro immediately after type II cell isolation, Ts increased 2‐fold and TG2/M rose up to 10‐fold above the value obtained in vivo. After 2 d of primary culture under customary plating conditions, Ts had returned to the same value as that in vivo, but TG2/M remained elevated. Little variability was observed in the duration of S‐phase within each treatment group. In contrast, type II cells exhibited considerable heterogeneity in the rate of G2/M‐phase traverse, especially in vitro. These data suggest that the inability of adult rat type II pneumocytes to proliferate in primary culture is related to delayed G2/M‐phase transit and imply the existence of pneumocyte subpopulations which differ in susceptibility to growth arrest. © 1994 Wiley‐Liss, Inc.
Streptavidin‐tricolor is a reliable marker for nonviable cells subjected to permeabilization or fixation
Authors: Levelt Christiaan N. , Eichmann Klaus 
Published: June 2005

AbstractCell death is normally accompanied by loss of integrity of the cell membrane. Concomitant loss of osmotic pressure and permeability for DNA binding dyes like propidium iodide make it possible to distinguish viable from nonviable cells. However, after permeabilization for intracellular staining or after fixation of the cells, we find that propidium iodide leaks out of nonviable cells and is transferred to formerly viable cells. Cell size cannot be used for examining viability in permeabilized or heterogeneous cell populations. Here we show that streptavidintricolor enters specifically and irreversibly into dead cells, and is not transferred to formerly viable cells after fixation or permeabilization. Therefore, streptavidin‐tricolor can be a useful dead‐cell marker in experimental situations where conventional methods fail to distinguish between viable and nonviable cells. © 1994 Wiley‐Liss, Inc.
Flow cytometric detection of apoptosis: Comparison of the assays of in situ DNA degradation and chromatin changes
Authors: Hotz Michel A. , Gong Jianping , Traganos Frank , Darzynkiewicz Zbigniew 
Published: June 2005

AbstractThe aim of this study was to compare three methods of detection of apoptotic cells: (1) the method based on elution of low molecular weight DNA from the ethanol fixed cells followed by cell staining with DAPI (diamidino‐2–phenylindole) or propidium iodide as the DNA fluorochromes, (2) the method of in situ labeling of DNA strand breaks with biotinylated dUTP, utilizing exogenous terminal deoxyribonucleotide transferase, and (3) the method of analysis of DNA denaturation in situ using acridine orange to differentially stain denatured and doublestranded DNA sections following cell exposure to 0.1 M HCl. Cells of the human promyelocytic HL‐60 line, treated in vitro with the DNA topoisomerase I inhibitor camptothecin, which selectively triggers apoptosis of S‐phase cells, were chosen as a model. The method based on analysis of changes in DNA denaturability was the most sensitive in terms of detection of the earliest changes in chromatin of cells undergoing apoptosis; the increased sensitivity of DNA to denaturation in Sphase cells was measured as early as 100 min after addition of camptothecin. DNA cleavage, assayed either by the univariate measurement of DNA content following extraction of low molecular weight DNA, or by labeling DNA strand breaks with biotinylated dUTP, was detected in S‐phase cells after 120 min incubation with camptothecin. The percentage of apoptotic cells at the late stage of apoptosis, the kinetics of cell transition to apoptosis, and kinetics of the loss of S phase cells were all essentially similar when measured by any method. All three methods can be used to estimate the cell cycle phase specificity of apoptosis, although the method based on DNA strand labeling with biotinylated dUTP by terminal deoxynucleotidyl transferase has the advantage of making it possible to estimate the cell cycle distribution of both the apoptotic and unaffected cell populations. The latter method also appears to be the most specific in terms of detection of apoptosis. © 1994 Wiley‐Liss, Inc.