RESUMO
Activating mutations in GNAQ/GNA11 occur in over 90% of uveal melanomas (UMs), the most lethal melanoma subtype; however, targeting these oncogenes has proven challenging and inhibiting their downstream effectors show limited clinical efficacy. Here, we performed genome-scale CRISPR screens along with computational analyses of cancer dependency and gene expression datasets to identify the inositol-metabolizing phosphatase INPP5A as a selective dependency in GNAQ/11-mutant UM cells in vitro and in vivo. Mutant cells intrinsically produce high levels of the second messenger inositol 1,4,5 trisphosphate (IP3) that accumulate upon suppression of INPP5A, resulting in hyperactivation of IP3-receptor signaling, increased cytosolic calcium and p53-dependent apoptosis. Finally, we show that GNAQ/11-mutant UM cells and patients' tumors exhibit elevated levels of IP4, a biomarker of enhanced IP3 production; these high levels are abolished by GNAQ/11 inhibition and correlate with sensitivity to INPP5A depletion. Our findings uncover INPP5A as a synthetic lethal vulnerability and a potential therapeutic target for GNAQ/11-mutant-driven cancers.
Assuntos
Melanoma , Humanos , Melanoma/tratamento farmacológico , Subunidades alfa de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/uso terapêutico , Mutação , Transdução de Sinais , Inositol Polifosfato 5-Fosfatases/genéticaRESUMO
We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes.
Assuntos
Adenosina Trifosfatases/genética , Adenosina Trifosfatases/fisiologia , Evolução Biológica , Cromossomos/ultraestrutura , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Eucariotos/genética , Genoma , Complexos Multiproteicos/genética , Complexos Multiproteicos/fisiologia , Adenosina Trifosfatases/química , Algoritmos , Animais , Nucléolo Celular/ultraestrutura , Núcleo Celular/ultraestrutura , Centrômero/ultraestrutura , Cromossomos/química , Cromossomos Humanos/química , Cromossomos Humanos/ultraestrutura , Proteínas de Ligação a DNA/química , Genoma Humano , Genômica , Heterocromatina/ultraestrutura , Humanos , Interfase , Mitose , Modelos Biológicos , Complexos Multiproteicos/química , Telômero/ultraestruturaRESUMO
Condensin is a conserved SMC complex that uses its ATPase machinery to structure genomes, but how it does so is largely unknown. We show that condensin's ATPase has a dual role in chromosome condensation. Mutation of one ATPase site impairs condensation, while mutating the second site results in hyperactive condensin that compacts DNA faster than wild-type, both in vivo and in vitro. Whereas one site drives loop formation, the second site is involved in the formation of more stable higher-order Z loop structures. Using hyperactive condensin I, we reveal that condensin II is not intrinsically needed for the shortening of mitotic chromosomes. Condensin II rather is required for a straight chromosomal axis and enables faithful chromosome segregation by counteracting the formation of ultrafine DNA bridges. SMC complexes with distinct roles for each ATPase site likely reflect a universal principle that enables these molecular machines to intricately control chromosome architecture.
Assuntos
Adenosina Trifosfatases/metabolismo , Montagem e Desmontagem da Cromatina/fisiologia , Proteínas de Ligação a DNA/metabolismo , Complexos Multiproteicos/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/fisiologia , Trifosfato de Adenosina/química , Sítios de Ligação/genética , Sítios de Ligação/fisiologia , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Cromatina/fisiologia , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos/metabolismo , Cromossomos/fisiologia , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Humanos , Complexos Multiproteicos/fisiologia , Ligação Proteica/fisiologia , Subunidades Proteicas/metabolismo , CoesinasRESUMO
Cohesin stably holds together the sister chromatids from S phase until mitosis. To do so, cohesin must be protected against its cellular antagonist Wapl. Eco1 acetylates cohesin's Smc3 subunit, which locks together the sister DNAs. We used yeast genetics to dissect how Wapl drives cohesin from chromatin and identified mutants of cohesin that are impaired in ATPase activity but remarkably confer robust cohesion that bypasses the need for the cohesin protectors Eco1 in yeast and Sororin in human cells. We uncover a functional asymmetry within the heart of cohesin's highly conserved ABC-like ATPase machinery and find that both ATPase sites contribute to DNA loading, whereas DNA release is controlled specifically by one site. We propose that Smc3 acetylation locks cohesin rings around the sister chromatids by counteracting an activity associated with one of cohesin's two ATPase sites.
Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , DNA/metabolismo , Proteínas Nucleares/metabolismo , Saccharomyces cerevisiae/genética , Acetilação , Domínio Catalítico , Ciclo Celular , Cromatina/genética , Humanos , Proteínas Nucleares/química , Proteínas Nucleares/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , CoesinasRESUMO
The X shape of chromosomes is one of the iconic images in biology. Cohesin actually connects the sister chromatids along their entire length, from S phase until mitosis. Then, cohesin's antagonist Wapl allows the separation of chromosome arms by opening a DNA exit gate in cohesin rings. Centromeres are protected against this removal activity, resulting in the X shape of mitotic chromosomes. The destruction of the remaining centromeric cohesin by Separase triggers chromosome segregation. We review the two-phase regulation of cohesin removal and discuss how this affects chromosome alignment and decatenation in mitosis and cohesin reloading in the next cell cycle.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Estruturas Cromossômicas/genética , Mitose , Animais , Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Estruturas Cromossômicas/metabolismo , Humanos , CoesinasRESUMO
Chromosomal instability is a driving force for heterogeneity within tumours. A recent study shows that boosting sister chromatid cohesion corrects chromosomal instability in pRB-deficient cancer cells. This key finding provides an important lead to make tumours more susceptible to anti-cancer drugs.
Assuntos
Proteínas de Ciclo Celular/genética , Transformação Celular Neoplásica/genética , Instabilidade Cromossômica , Proteínas Cromossômicas não Histona/genética , Regulação Neoplásica da Expressão Gênica , Histonas/genética , Proteína do Retinoblastoma/genética , HumanosRESUMO
Glioblastoma multiforme (GBM) is the most common primary brain cancer in adults and there are few effective treatments. GBMs contain cells with molecular and cellular characteristics of neural stem cells that drive tumour growth. Here we compare responses of human glioblastoma-derived neural stem (GNS) cells and genetically normal neural stem (NS) cells to a panel of 160 small molecule kinase inhibitors. We used live-cell imaging and high content image analysis tools and identified JNJ-10198409 (J101) as an agent that induces mitotic arrest at prometaphase in GNS cells but not NS cells. Antibody microarrays and kinase profiling suggested that J101 responses are triggered by suppression of the active phosphorylated form of polo-like kinase 1 (Plk1) (phospho T210), with resultant spindle defects and arrest at prometaphase. We found that potent and specific Plk1 inhibitors already in clinical development (BI 2536, BI 6727 and GSK 461364) phenocopied J101 and were selective against GNS cells. Using a porcine brain endothelial cell blood-brain barrier model we also observed that these compounds exhibited greater blood-brain barrier permeability in vitro than J101. Our analysis of mouse mutant NS cells (INK4a/ARF(-/-), or p53(-/-)), as well as the acute genetic deletion of p53 from a conditional p53 floxed NS cell line, suggests that the sensitivity of GNS cells to BI 2536 or J101 may be explained by the lack of a p53-mediated compensatory pathway. Together these data indicate that GBM stem cells are acutely susceptible to proliferative disruption by Plk1 inhibitors and that such agents may have immediate therapeutic value.
Assuntos
Proteínas de Ciclo Celular/antagonistas & inibidores , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neurais/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Animais , Benzimidazóis/farmacologia , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Western Blotting , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Glioblastoma/enzimologia , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Indanos/farmacologia , Camundongos , Camundongos Knockout , Células-Tronco Neoplásicas/enzimologia , Células-Tronco Neoplásicas/patologia , Células-Tronco Neurais/enzimologia , Células-Tronco Neurais/patologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Pteridinas/farmacologia , Pirazóis/farmacologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Suínos , Tiofenos/farmacologia , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Quinase 1 Polo-LikeRESUMO
The classical X shape of mitotic human chromosomes is the consequence of two distinct waves of cohesin removal. First, during prophase and prometaphase, the bulk of cohesin is driven from chromosome arms by the cohesin antagonist WAPL. This arm-specific cohesin removal is referred to as the prophase pathway [1-4]. The subsequent cleavage of the remaining centromeric cohesin by Separase is known to be the trigger for anaphase onset [5-7]. Remarkably the biological purpose of the prophase pathway is unknown. We find that this pathway is essential for two key mitotic processes. First, it is important to focus Aurora B at centromeres to allow efficient correction of erroneous microtubule-kinetochore attachments. In addition, it is required to facilitate the timely decatenation of sister chromatids. As a consequence, WAPL-depleted cells undergo anaphase with segregation errors, including both lagging chromosomes and catenanes, resulting in micronuclei and DNA damage. Stable WAPL depletion arrests cells in a p53-dependent manner but causes p53-deficient cells to become highly aneuploid. Our data show that the WAPL-dependent prophase pathway is essential for proper chromosome segregation and is crucial to maintain genomic integrity.
Assuntos
Aneuploidia , Proteínas de Transporte/genética , Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Segregação de Cromossomos , Proteínas Nucleares/genética , Prófase , Proteínas Proto-Oncogênicas/genética , Aurora Quinase B/genética , Aurora Quinase B/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Centrômero/metabolismo , Cromátides/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos Humanos/metabolismo , Humanos , Microscopia de Contraste de Fase , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Epitélio Pigmentado da Retina , CoesinasRESUMO
This is the largest Libyan study to date to investigate the prevalence and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) among health care workers in Tripoli, Libya. A total of 569 doctors and nurses from 4 main hospitals were screened for MRSA with specimens collected from the anterior nares. Isolates from 109 of the 569 subjects (19%) were confirmed as MRSA by polymerase chain reaction assay; the majority (98/109) were from a general hospital. Antimicrobial resistance patterns tested by disk diffusion were as follows: erythromycin (74%), ciprofloxacin (77%), clindamycin (20%), trimethoprim/sulfamethoxazole (50%), quinuprisin/dalfopristin (19%), vancomycin (12%) and mupirocin (5%). Eighteen isolates exhibited macrolide-lincosamide-streptogramin B resistance (MLSB): 6 were MLSBi and 12 were MLSBc. The results provide evidence that Libyan health care workers could serve as MRSA carriers and play a role in the dissemination of MRSA to the public and other workers.
Assuntos
Portador Sadio/prevenção & controle , Transmissão de Doença Infecciosa do Profissional para o Paciente/prevenção & controle , Programas de Rastreamento , Staphylococcus aureus Resistente à Meticilina , Recursos Humanos em Hospital , Infecções Estafilocócicas/prevenção & controle , Portador Sadio/epidemiologia , Humanos , Líbia/epidemiologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Prevalência , Fatores de Risco , Infecções Estafilocócicas/epidemiologiaRESUMO
Brucellosis is a global zoonotic disease, endemic in North African countries and around the Mediterranean.A prospective study of Brucella seroprevalence was conducted in north-western Libya (western mountains region). Blood samples collected over 13 months in the period December 2006 to January 2008 from 561 animals (goats, sheep, cattle and camels) and 546 human volunteers were tested for Brucella using the Rose Bengal test, tube agglutination test and ELISA assays. Amongst livestock, 31% of goats and 42% of cattle were seropositive. Human samples showed a high seropositivity of 40%, with 95 (43%) of the 221 positive samples positive for IgM, indicating active or recent infection. Control measures are needed to reduce this high prevalence of brucellosis in Libya.
Assuntos
Anticorpos Antibacterianos/sangue , Brucella/imunologia , Brucelose/sangue , Brucelose/veterinária , Animais , Brucelose/epidemiologia , Feminino , Humanos , Líbia/epidemiologia , Masculino , Estudos Prospectivos , Estudos SoroepidemiológicosRESUMO
We report a new route for the design of electroluminescent polymers by grafting high-efficiency phosphorescent organometallic complexes as dopants and charge transport moieties onto alky side chains of fully conjugated polymers for polymer light-emitting diodes (PLED) with single layer/single polymers. The polymer system studied involves polyfluorene (PF) as the base conjugated polymer, carbazole (Cz) as the charge transport moiety and a source for green emission by forming an electroplex with the PF main chain, and cyclometalated iridium (Ir) complexes as the phosphorescent dopant. Energy transfer from the green Ir complex or an electroplex formed between the fluorene main chain and side-chain carbazole moieties, in addition to that from the PF main chain, to the red Ir complex can significantly enhance the device performance, and a red light-emitting device with the high efficiency 2.8 cd/A at 7 V and 65 cd/m2, comparable to that of the same Ir complex-based OLED, and a broad-band light-emitting device containing blue, green, and red peaks (2.16 cd/A at 9 V) are obtained.
RESUMO
Kinetics of solid state stability of seven derivatives of 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) of glycine as a model for amino acids and peptide drugs were studied using differential scanning calorimetry (DSC). Each DSC curve for each derivative showed an endothermic peak followed by an exothermic one, which could be attributed to the melting and decomposition, respectively. The decomposition activation energy of each derivative was calculated using the Augis and Bennet, Kissinger equations and Mahadevan approximation. Also, the melting activation energies as well as the thermodynamic parameter (enthalpy) for the investigated derivatives were evaluated. The relative stability of the derivatives in the solid state according to the calculated values of the decomposition activation energy, frequency factors and half-life for each derivative could be determined.
Assuntos
Varredura Diferencial de Calorimetria/métodos , Glicina/metabolismo , Peptídeos/metabolismo , Tiadiazinas/metabolismo , Estabilidade de Medicamentos , Cinética , Modelos QuímicosRESUMO
The objective of this study was to determine the impact of a series of nonionic surfactants on the solubility of piperazine-containing drug (meclizine, MZ) in comparison to that of natural cyclodextrins (alpha-CD and beta-CD) and dimethyl-beta-cyclodextrin (DM-beta-CD). The solubility of the drug was studied in either CDs solutions or nonionic surfactant solutions. Three classes of nonionic surfactants were used namely; polyoxyethylene (POE) sorbitan fatty acid esters (polysorbates), POE fatty acid esters (Myrjs) and polyethylene oxide (PEO) fatty alcohol ethers (Brijs and Eumulgins). The solubility of MZ was increased linearly with the increasing surfactant concentration, indicating that micellar solubilization follows the partition model. It was found that the longer the hydrocarbon chain in a homologous series, the more efficient is the solubilizing power of surfactant. For example, polysorbate 80 (Tween-80) is a more efficient solubilizer than polysorbate 20 (Tween-20), indicating that the drug was incorporated in the core of micelle more than the capsular region of the micelle. On the other hand, in case of POE fatty acid esters, the solubilizing power increased with decreasing polyoxyethylene chain as Myrj 53 was more efficient than Myrj 59. In class of PEO fatty alcohol ethers, the shorter the hydrophilic chain and longer lipophilic chain, the more efficient was the solubilizing capacity. Thus, Brij 58 was more efficient solubilizer than Brij 35 and Eumulgin C1000 was more active than Eumulgin C1500. Comparatively, Eumulgin C1000 had the highest solubilizing power for MZ among the studied PEO fatty alcohol ethers and other groups of surfactants. The solubility action of surfactants toward MZ was increased by raising the temperature of the surfactant solutions from 30 to 45 degrees C. Hydrophilic macromolecules (PEG 1000 and PEG 6000) or cosolvents (glycerol and propylene glycol) have a very slight effect on the solubility of MZ and confirm the predominance of hydrophobic interaction between the drug and nonionic surfactants. A(L)-type phase solubility diagrams were obtained for the drug with alpha-, beta- and DM-beta-CDs showing that the solubility of MZ was enhanced through inclusion complexation. Comparatively, DM-beta-CD had the highest solubilizing efficiency for the drug among the investigated CDs, which could be attributed to its larger hydrophobic cavity size.
Assuntos
Ciclodextrinas/química , Meclizina/química , Tensoativos/química , Antialérgicos/química , Química Farmacêutica , Portadores de Fármacos/química , SolubilidadeRESUMO
Two alternate allelic forms of human cytosine 5-methyltransferase, 5-MT I and 5-MT II, which differ by the absence or presence of an intronic MspI recognition sequence, have been recognised. The polymorphic region was localised using a series of subprobes prepared upon MspI digestion of the 2.5-kb cDNA probe (hmt-2.5). A PCR-based method was then developed for rapid 5-MT genotyping. The gene and phenotype frequencies of 5-MT I and 5-MT II were not significantly different in genomic DNA samples from a series of non-Hodgkin's lymphomas and breast cancer cases compared with DNA from normal subjects. Allelism of 5-MT allows new approaches to the assessment of variation in gene copy number of 5-MT in different types of neoplasia.
Assuntos
Neoplasias da Mama/genética , DNA (Citosina-5-)-Metiltransferases/genética , Linfoma não Hodgkin/genética , Reação em Cadeia da Polimerase/métodos , Polimorfismo de Fragmento de Restrição , Alelos , DNA-Citosina Metilases , Desoxirribonucleases de Sítio Específico do Tipo II , Feminino , Dosagem de Genes , Frequência do Gene , Humanos , Íntrons , Masculino , FenótipoRESUMO
Sustained release cellulose acetate butyrate (CAB)-polystyrene (PS) microcapsules containing ketoprofen (a non-steroidal anti-inflammatory drug) were prepared adopting the modified W/O/W complex emulsion technique. The effect of polystyrene concentration and core/coat ratio on the yield, geometric mean particle diameter, dg, size distribution, drug loading as well as release and surface characteristics of the microcapsules was investigated. The results obtained revealed that polystyrene utilization as a wall material plays a dominant role in the manufacturing process. A particular composition of 92 center dot 5: 7 center dot 5 (%) of CAB to PS was found to improve greatly the microcapsule yield and maximize the drug loading. In most cases, the encapsulation efficiencies increased with increasing microcapsule size and theoretical drug loading. Kinetic analysis of the data shows that the drug release process from CAB microcapsules followed Higuchi model (a diffusion-controlled model for a planar matrix), whereas the release behaviour conforms with Baker and Lonsdale model (a diffusion-controlled model for a spherical matrix) for CAB-PS microcapsules. The preparation of free films of CAB and CAB-PS was described for comparison. The effect of processing parameters (polystyrene concentration, total polymers concentration and permeant concentration) on the permeation of ketoprofen through the polymeric films was discussed. The results demonstrated that ketoprofen permeation through the films and microcapsules could be controlled by modifying the CAB-PS ratio in the polymer matrices. The permeability constants lowered with increasing total polymers concentration up to 5% and were proportional to permeant concentration. To compare the kinetics of drug release from polymeric films with those of microcapsules, ketoprofen was incorporated at different concentrations within CAB-PS cast films. These films exhibited sustained release of the drug (t0 center dot 5; 58-146 h). Release rates were found to agree with the Baker and Lonsdale model, previously suggested for ketoprofen release from CAB-PS microcapsules.
Assuntos
Composição de Medicamentos , Cetoprofeno/metabolismo , Anti-Inflamatórios não Esteroides/metabolismo , Cápsulas/química , Cápsulas/metabolismo , Celulose/análogos & derivados , Celulose/metabolismo , Preparações de Ação Retardada/química , Preparações de Ação Retardada/metabolismo , Difusão , Portadores de Fármacos , Composição de Medicamentos/métodos , Excipientes/química , Excipientes/metabolismo , Cinética , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Permeabilidade , Poliestirenos/metabolismoRESUMO
Nitrazepam was found to form an inclusion complex with heptakis; 2,6 di-O-methyl-beta-cyclodextrin (DM-beta-CD) in solution. The phase solubility diagram was found to be AL type with no precipitation of the inclusion complex formed. The kinetic studies of nitrazepam hydrolysis in DM-beta-CD solution at 30, 40 and 50 degrees C was followed spectrophotometrically, as the degradation products of the drug did not interfere with such assay. It was found that the degradation of nitrazepam in acidic media followed the first order reaction kinetics at the temperatures studied. Inclusion complexation of nitrazepam in DM-beta-CD resulted in a relatively improved stability of the drug in solution at 30 degrees C. On the other hand, no appreciable stabilization was achieved at higher temperatures (40 and 50 degrees C).
Assuntos
Ciclodextrinas/química , Nitrazepam/química , beta-Ciclodextrinas , Estabilidade de Medicamentos , Hidrólise , CinéticaRESUMO
Inclusion complexes of clobazam with alpha-, beta-, gamma-cyclodextrins (CyDs) and heptakis(2.6-di-O-methyl)-beta-cyclodextrin (DM-beta-CyD) in aqueous solution and in the solid phase were studied by the solubility method, infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffractometry. In addition, inclusion complex of clobazam with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin and the solid dispersion of clobazam with methyl cellulose (MC) in a ground mixture were investigated by IR, DSC and X-ray diffractometry. It was observed that DM-beta-CyD had the highest stability constant among the four CyDs in solution. Thermal and X-ray diffraction analyses showed that clobazam molecules existed in a molecularly dispersed state in the ground mixture of CyDs. Infrared spectra showed lower frequency shifts in the case of the ground mixtures of clobazam with natural CyDs, which can be attributed to the formation of hydrogen bonds between the two carbonyl groups of clobazam and hydroxyl groups of natural CyDs. In contrast, higher frequency shifts were observed in the case of the ground mixtures of clobazam with methylated CyDs and MC and these were considered to be due to the monomolecular dispersion of clobazam in a hydrophobic environment. The mode of interaction of clobazam with DM-beta-CyD was different from that with natural CyDs in the ground mixtures. Furthermore, the crystalline inclusion complex of clobazam with DM-beta-CyD was obtained by heating of the coprecipitate in vacuo at 120 degrees C for 1 h.