Oncology phase I trial design and conduct: time for a change - MDICT Guidelines 2022.

In 2021, the Food and Drug Administration Oncology Center of Excellence announced Project Optimus focusing on dose optimization for oncology drugs. The Methodology for the Development of Innovative Cancer Therapies (MDICT) Taskforce met to review and discuss the optimization of dosage for oncology trials and to develop a practical guide for oncology phase I trials. Defining a single recommended phase II dose based on toxicity may define doses that are neither the most effective nor the best tolerated. MDICT recommendations address the need for robust non-clinical data which are needed to inform trial design, as well as an expert team including statisticians and pharmacologists. The protocol must be flexible and adaptive, with clear definition of all endpoints. Health authorities should be consulted early and regularly. Strategies such as randomization, intrapatient dose escalation, and real-world eligibility criteria are encouraged whereas serial tumor sampling is discouraged in the absence of a strong rationale and appropriately validated assay. Endpoints should include consideration of all longitudinal toxicity. The phase I dose escalation trial should define the recommended dose range for later testing in randomized phase II trials, rather than a single recommended phase II dose, and consider scenarios where different populations may require different dosages. The adoption of these recommendations will improve dosage selection in early clinical trials of new anticancer treatments and ultimately, outcomes for patients.

Association between morbidity among term newborns and low-risk caesarean delivery rates.

OBJECTIVE: To examine the association between county-level caesarean delivery (CD) rates among women at low risk and morbidity among term newborns. DESIGN: Cross-sectional study. SETTING: Population-based study of US county-level birth data from 2015 to 2017. POPULATION: Nulliparous women with term, singleton, vertex-presenting infants (NTSV) at low risk for morbidity. METHODS: The primary exposure was county-level CD rates. MAIN OUTCOME MEASURES: The outcome was morbidity among the low-risk NTSV cohort, categorised as severe (5-minute Apgar score of ≤3, assisted ventilation for ≥6 hours, severe neurologic injury or seizure, transfer or death) or moderate (5-minute Apgar score of <7 but >3, administration of antibiotics or assisted ventilation at delivery). We used linear regression models to determine the association between county NTSV CD and neonatal morbidity rates with cluster robust standard errors. RESULTS: The analysis included data from 2 753 522 births in 952 counties from all 48 states. The mean NTSV CD rate was 23.6% (standard deviation 4.8%). The median severe and moderate neonatal morbidity rates were 15.2 (interquartile range, IQR 9.4-23.6) and 52.5 (IQR 33.4-75.7) per 1000 births, respectively. In the unadjusted analysis using the risk-adjusted exposure and outcome, every percentage point increase in the CD rate of a county was associated with 0.6 (95% CI -0.9, -0.3) and 2.3 fewer (95% CI -3.4, -1.1) cases of severe and moderate neonatal morbidity per 1000 live births. After adjustment for other county factors, the relationships remained significant. These findings were tested in multiple sensitivity analyses. CONCLUSIONS: Lower county-level NTSV CD rates were associated with a small increase in morbidity among term newborns in the USA. TWEETABLE ABSTRACT: Lower county-level caesarean delivery rates were associated with an increase in morbidity among term newborns in the USA.

The impact of different hair-removal behaviours on the biophysical and biochemical characteristics of female axillary skin.

OBJECTIVE: The impact of hair removal on the biophysical and biochemical characteristics of human axillary skin is not fully understood. This study investigated the effect of different hair-removal techniques on biophysical parameters and the concentrations of key inflammatory biomarkers in the axillae of female Thai subjects. Axillary hair was removed by shaving, plucking or waxing. METHODS: Following a 2-week washout phase without hair removal, subjects underwent visual assessment for erythema and skin dryness in one (randomized) axilla, then, hair was removed from the axilla by shaving, plucking or waxing according to each subject's established habit. Erythema and dryness were assessed again 30 min after hair removal, and buffer scrubs collected from depilated and non-depilated axillae and analysed for inflammatory cytokines; after a further 48 h, erythema, dryness and post-inflammatory hyperpigmentation (PIHP) were assessed in the depilated axilla. Biophysical assessments (skin hydration, barrier integrity, elasticity and roughness) were made in depilated and non-depilated axillae. RESULTS: All three hair-removal techniques induced an increase in axillary erythema and skin dryness. Shaving was associated with significantly less erythema (P < 0.01), but significantly greater skin dryness (P < 0.05) versus the other techniques 30 min after hair removal. There were no between-technique differences in PIHP or biophysical parameters. Interleukins IL-1α and IL-1RA concentrations increased, and IL-8 concentration decreased following hair removal by each technique. CONCLUSION: This is the first study to identify the principal cytokines associated with the inflammatory process triggered by axillary hair removal. A single hair-removal treatment did not appear to induce PIHP or further biophysical changes to the skin.

OBJECTIF: L'impact de l'épilation sur les caractéristiques biophysiques et biochimiques de la peau axillaire humaine n'est pas entièrement compris. Cette étude a examiné l'effet de différentes techniques d'épilation sur les paramètres biophysiques et les concentrations de biomarqueurs inflammatoires clés dans les aisselles de sujets thaïlandais de sexe féminin. Les aisselles ont été épilées par rasage, à la pince ou à la cire. MÉTHODES: Après une phase de sevrage de 2 semaines sans épilation, les sujets ont subi une évaluation visuelle de l'érythème et de la sécheresse cutanée dans une aisselle (randomisé), puis l'aisselle a été épilée par rasage, à la pince ou à la cire selon l'habitude établie de chaque sujet. L'érythème et la sécheresse ont été évalués à nouveau 30 minutes après l'épilation, et des frottis tampons ont été prélevés dans les aisselles épilées et non épilées et analysés pour détecter les cytokines inflammatoires; puis, après 48 heures, l'érythème, la sécheresse et l'hyperpigmentation post-inflammatoire (PIHP) ont été évalués dans les aisselles épilées. Des évaluations biophysiques (hydratation cutanée, intégrité de la barrière cutanée, élasticité et rugosité de la peau) ont été réalisées sur les aisselles épilées et non épilées. RÉSULTATS: Les trois techniques d'épilation ont entraîné une accentuation de l'érythème axillaire et de la sécheresse de la peau. Le rasage a été associé à un érythème nettement moins important (P < 0,01), mais à une sécheresse cutanée nettement plus importante (P < 0,05) par rapport aux autres techniques 30 min après l'épilation. Aucune différence entre les techniques n'a été observée en ce qui concerne le PIHP ou les paramètres biophysiques. Les concentrations en interleukines IL-1α IL-1RA ont augmenté, et la concentration en IL-8 a diminué après l'épilation par chaque technique. CONCLUSION: Cette étude est la première à identifier les cytokines principales associées au processus inflammatoire déclenché par l'épilation des aisselles. Une seule épilation n'a pas semblé entraîner de PIHP ou d'autres modifications biophysiques de la peau.

The linker region of breast cancer resistance protein ABCG2 is critical for coupling of ATP-dependent drug transport.

The ATP-binding cassette (ABC) transporters of class G display a different domain organisation than P-glycoprotein/ABCB1 and bacterial homologues with a nucleotide-binding domain preceding the transmembrane domain. The linker region connecting these domains is unique and its function and structure cannot be predicted. Sequence analysis revealed that the human ABCG2 linker contains a LSGGE sequence, homologous to the canonical C-motif/ABC signature present in all ABC nucleotide-binding domains. Predictions of disorder and of secondary structures indicated that this C2-sequence was highly mobile and located between an α-helix and a loop similarly to the C-motif. Point mutations of the two first residues of the C2-sequence fully abolished the transport-coupled ATPase activity, and led to the complete loss of cell resistance to mitoxantrone. The interaction with potent, selective and non-competitive, ABCG2 inhibitors was also significantly altered upon mutation. These results suggest an important mechanistic role for the C2-sequence of the ABCG2 linker region in ATP binding and/or hydrolysis coupled to drug efflux.

ANG1005 for breast cancer brain metastases: correlation between 18F-FLT-PET after first cycle and MRI in response assessment.

PURPOSE: Improved therapies and imaging modalities are needed for the treatment of breast cancer brain metastases (BCBM). ANG1005 is a drug conjugate consisting of paclitaxel covalently linked to Angiopep-2, designed to cross the blood-brain barrier. We conducted a biomarker substudy to evaluate 18F-FLT-PET for response assessment. METHODS: Ten patients with measurable BCBM received ANG1005 at a dose of 550 mg/m2 IV every 21 days. Before and after cycle 1, patients underwent PET imaging with 18F-FLT, a thymidine analog, retention of which reflects cellular proliferation, for comparison with gadolinium-contrast magnetic resonance imaging (Gd-MRI) in brain metastases detection and response assessment. A 20 % change in uptake after one cycle of ANG1005 was deemed significant. RESULTS: Thirty-two target and twenty non-target metastatic brain lesions were analyzed. The median tumor reduction by MRI after cycle 1 was -17.5 % (n = 10 patients, lower, upper quartiles: -25.5, -4.8 %) in target lesion size compared with baseline. Fifteen of twenty-nine target lesions (52 %) and 12/20 nontarget lesions (60 %) showed a ≥20 % decrease post-therapy in FLT-PET SUV change (odds ratio 0.71, 95 % CI: 0.19, 2.61). The median percentage change in SUVmax was -20.9 % (n = 29 lesions; lower, upper quartiles: -42.4, 2.0 %), and the median percentage change in SUV80 was also -20.9 % (n = 29; lower, upper quartiles: -49.0, 0.0 %). Two patients had confirmed partial responses by PET and MRI lasting 6 and 18 cycles, respectively. Seven patients had stable disease, receiving a median of six cycles. CONCLUSIONS: ANG1005 warrants further study in BCBM. Results demonstrated a moderately strong association between MRI and 18F-FLT-PET imaging.

Primary care and population factors associated with NHS Health Check coverage: a national cross-sectional study.

INTRODUCTION: High and equitable coverage of systematic cardiovascular disease (CVD) prevention programmes, such as the NHS Health Check programme in England, is essential if they are to effectively reduce the population CVD burden. METHODS: We conducted a cross-sectional study using data from 151 English primary care trusts (PCTs) on NHS Health Check coverage during 2011-12. We examined the associations between programme coverage and primary care and population factors, including patient demographics, primary care workforce and cardiovascular health need. RESULTS: Median coverage of NHS Health Checks was 8.2%, with wide PCT-level variation (range = 0-29.8%). Coverage was significantly higher in PCTs in the most deprived areas compared with the least deprived (P = 0.035), adjusting for covariates. Significant negative associations between coverage and a higher proportion of PCT population aged 40-74 years-the eligible Health Check age group, a larger total population size and higher practice staffing levels were found in the unadjusted analyses. CONCLUSIONS: NHS Health Check coverage during 2011-12 was lower than the government projection of 18% coverage. Coverage must be increased through concerted multi-disciplinary strategies, for the programme to improve cardiovascular health in England. Considerable variation in participation between PCTs warrants attention, with enhanced support for poor performers.

Epigenetic inactivation of a RAS association domain family protein from the lung tumour suppressor locus 3p21.3.

Allelic loss at the short arm of chromosome 3 is one of the most common and earliest events in the pathogenesis of lung cancer, and is observed in more than 90% of small-cell lung cancers (SCLCs) and in 50-80% of non-small-cell lung cancers (NSCLCs). Frequent and early loss of heterozygosity and the presence of homozygous deletions suggested a critical role of the region 3p21.3 in tumorigenesis and a region of common homozygous deletion in 3p21.3 was narrowed to 120 kb (ref. 5). Several putative tumour-suppressor genes located at 3p21 have been characterized, but none of these genes appear to be altered in lung cancer. Here we describe the cloning and characterization of a human RAS effector homologue (RASSF1) located in the 120-kb region of minimal homozygous deletion. We identified three transcripts, A, B and C, derived from alternative splicing and promoter usage. The major transcripts A and C were expressed in all normal tissues. Transcript A was missing in all SCLC cell lines analysed and in several other cancer cell lines. Loss of expression was correlated with methylation of the CpG-island promoter sequence of RASSF1A. The promoter was highly methylated in 24 of 60 (40%) primary lung tumours, and 4 of 41 tumours analysed carried missense mutations. Re-expression of transcript A in lung carcinoma cells reduced colony formation, suppressed anchorage-independent growth and inhibited tumour formation in nude mice. These characteristics indicate a potential role for RASSF1A as a lung tumour suppressor gene.

Low-dose electron beam radiation and romidepsin therapy for symptomatic cutaneous T-cell lymphoma lesions.

BACKGROUND: Romidepsin is a structurally unique histone deacetylase inhibitor approved by the U.S. Food and Drug Administration for therapy of relapsed or refractory cutaneous T-cell lymphoma (CTCL). Localized electron beam radiation therapy (LEBT) is standard practice in the care of patients with chronically traumatized and painful lesions. Combination therapy of those two modalities may be beneficial for the therapy of CTCL. OBJECTIVES: To report observations on supportive LEBT utilized for isolated refractory lesions in patients on romidepsin. METHODS: Observations were made during a phase II clinical trial sponsored by the National Cancer Institute (NCI-1312) examining the efficacy of romidepsin for patients with relapsed, refractory or advanced CTCL, stage IB-IVA mycosis fungoides (MF) or Sézary syndrome. Skin responses were assessed by evaluation of five target lesions only. Patients with objective clinical responses in target lesions who had symptomatic nontarget lesions were allowed limited LEBT to isolated lesions for symptomatic relief. Patients who received localized radiation were not considered complete responders at any point. RESULTS: Five patients with advanced MF (three stage IIB and two stage IVA2) received LEBT to symptomatic nontarget lesions while on a protocol with romidepsin. None of these patients experienced additional or unexpected toxicity. Four of the five patients demonstrated fast and durable responses. We noted that significantly lower than standard doses of LEBT effectively treated symptomatic lesions in these patients. CONCLUSIONS: LEBT demonstrated significant responses at very low doses without additional toxicity in patients on protocol treatment with the histone deacetylase inhibitor romidepsin. This merits formal investigation in a clinical trial for potential synergy in patients with CTCL.

The high-pressure electronic structure of the [Ni(ptdt)2] organic molecular conductor.

The electronic structure of the single component molecular crystal [Ni(ptdt)(2)] (ptdt = propylenedithiotetrathiafulvalenedithiolate) is determined at ambient and high pressure using density functional theory. The electronic structure of this crystal is found to be of the "crossing bands" type with respect to the dispersion of the HOMO and LUMO, resulting in a small, non-zero density of states at the Fermi energy at ambient pressure, indicating that this crystal is a "poor quality" metal, and is consistent with the crystal's resistivity exhibiting a semiconductor-like temperature dependence. The ambient pressure band structure is found to be predominantly one-dimensional, reflecting enhanced intermolecular interactions along the [100] stacking direction. Our calculations indicate that the band structure becomes two-dimensional at high pressures and reveals the role of shortened intermolecular contacts in this phenomenon. The integrity of the molecular structure is found to be maintained up to at least 22 GPa. The electronic structure is found to exhibit a crossing bands nature up to 22 GPa, where enhanced intermolecular interactions increase the Brillouin zone centre HOMO-LUMO gap from 0.05 eV at ambient pressure to 0.15 eV at 22 GPa; this enhanced HOMO-LUMO interaction ensures that enhancement of a metallic state in this crystal cannot be simply achieved through the application of pressure, but rather requires some rearrangement of the molecular packing. Enhanced HOMO-LUMO interactions result in a small density of states at the Fermi energy for the high pressure window 19.8-22 GPa, and our calculations show that there is no change in the nature of the electronic structure at the Fermi energy for these pressures. We correspondingly find no evidence of an electronic semiconducting-metal insulator transition for these pressures, contrary to recent experimental evidence [Cui et al., J. Am. Chem. Soc. 131, 6358 (2009)].

Prevalence of paraproteinaemia in older Australians.

BACKGROUND: Estimates of the prevalence of paraproteinaemia vary, from 1% in persons aged over 25 years to 10% in those aged over 80 years, although there are limited data from well-defined populations. We sought to determine the prevalence of paraproteinaemia in Australians aged 50 years and over, and to determine risks factors for its presence. METHODS: We performed a population-based, cross-sectional study using data and serum collected in the Blue Mountains Eye Study. Serum samples from 2933 patients were analysed by capillary zone electrophoresis and, where indicated, immunosubtraction, which allowed for both quantitation and isotype detection. RESULTS: A paraprotein was detected in 134 of the 2933 samples, giving an overall prevalence of 4.6% (95% confidence interval, 3.8-5.3%). The presence of a paraprotein was strongly age-related (P(trend) = 0.001), with a prevalence of 2.8% in persons aged 50-59 years, rising steadily to 9.1% in those aged 80 years and over. The prevalence was significantly higher in men (5.9%) compared with women (4.0%) (P= 0.03). CONCLUSION: We conclude that approximately one in 20 Australians aged 50 years or over harbours a paraprotein, a prevalence that appears higher than from similar cohorts in other countries.

Changing knowledge and beliefs through an oral health pregnancy message.

OBJECTIVES: Pregnancy can be a critical and important period in which to intervene to improve oral health in both the mother and her child. This study examined an online approach for promoting awareness of oral health messages targeted at pregnant women, and whether this type of health messaging impacts oral health knowledge and beliefs. METHODS: The study was conducted in three parts: production and pilot testing of a brief commercial, Web site/commercial launch and testing, and dissemination and monitoring of the commercial on a video-sharing site. The brief commercial and pre- and postsurveys were produced and pilot tested among a convenience sample of pregnant women (n = 13). The revised commercial and surveys were launched on a newly created Web site and monitored for activity. After 2 months, the commercial was uploaded to a popular video-sharing Web site. RESULTS: Fifty-five individuals completed both the pre- and postsurveys after the Web site was launched. No one responded 100 percent correctly on the presurvey; 77.4 percent responded correctly about dental visits during pregnancy, 66.0 percent about cavity prevention, and 50.9 percent about transmission of bacteria by saliva. Most respondents recalled the correct information on the posttest; 100 percent or close to 100 percent accurately responded about visiting the dentist during pregnancy and preventing cavities, while 79.2 percent responded correctly to the transmission question. CONCLUSION: Social media can effectively provide dental health messages during pregnancy. This approach can play an important role in increasing awareness and improving oral health of both mother and child.

Analysis of gene expression in two large schizophrenia cohorts identifies multiple changes associated with nerve terminal function.

Schizophrenia is a severe psychiatric disorder with a world-wide prevalence of 1%. The pathophysiology of the illness is not understood, but is thought to have a strong genetic component with some environmental influences on aetiology. To gain further insight into disease mechanism, we used microarray technology to determine the expression of over 30 000 mRNA transcripts in post-mortem tissue from a brain region associated with the pathophysiology of the disease (Brodmann area 10: anterior prefrontal cortex) in 28 schizophrenic and 23 control patients. We then compared our study (Charing Cross Hospital prospective collection) with that of an independent prefrontal cortex dataset from the Harvard Brain Bank. We report the first direct comparison between two independent studies. A total of 51 gene expression changes have been identified that are common between the schizophrenia cohorts, and 49 show the same direction of disease-associated regulation. In particular, changes were observed in gene sets associated with synaptic vesicle recycling, transmitter release and cytoskeletal dynamics. This strongly suggests multiple, small but synergistic changes in gene expression that affect nerve terminal function.

An information-intensive approach to the molecular pharmacology of cancer.

Since 1990, the National Cancer Institute (NCI) has screened more than 60,000 compounds against a panel of 60 human cancer cell lines. The 50-percent growth-inhibitory concentration (GI50) for any single cell line is simply an index of cytotoxicity or cytostasis, but the patterns of 60 such GI50 values encode unexpectedly rich, detailed information on mechanisms of drug action and drug resistance. Each compound's pattern is like a fingerprint, essentially unique among the many billions of distinguishable possibilities. These activity patterns are being used in conjunction with molecular structural features of the tested agents to explore the NCI's database of more than 460,000 compounds, and they are providing insight into potential target molecules and modulators of activity in the 60 cell lines. For example, the information is being used to search for candidate anticancer drugs that are not dependent on intact p53 suppressor gene function for their activity. It remains to be seen how effective this information-intensive strategy will be at generating new clinically active agents.

Peptide aggregation and solvent electrostriction in a simple zwitterionic dipeptide via molecular dynamics simulations.

We investigate the structure of the glycyl-l-alanine dipeptide in aqueous solution at a 1:20 peptide:water concentration via classical, atomistic molecular dynamics simulations using the CHARMM22 force field, and compare to recent neutron diffraction data [S. E. McLain, A. K. Soper, and A. Watts, Eur. Biophys. J. 37, 647 (2008); S. E. McLain, A. K. Soper, I. Diadone, J. C. Smith, and A. Watts, Angew. Chem. Int. Ed. 47, 9059 (2008)]. Comparison between simulations and experiments is made using the static structure factor S(Q). The effect of water model (TIP3P, TIP4P, and SPC/E) upon the solution structure is investigated. Agreement between experiment and simulation is generally good across the entire Q range, although some model-dependent variation is observed, particularly in the predicted intensities of features in S(Q). Peptide aggregation is found to be driven by "hydrophilic" (often bifurcated) hydrogen bonds formed between carboxy and amine functional groups, although simulations suggest that the degree of aggregation is less than that observed experimentally. It is found that hydrophobic association is not significant, with hydrophobic hydration being preferred to association. Detailed examination of the solute structural motifs reveals the existence of bifurcated motifs that are suggested to be an artifact of the CHARMM force field, and may imply that classical force fields provide a flawed structural and dynamical description of such molecular fluids. Investigation of the water structure reveals the presence of an electrostrictive effect which manifests itself as an increase in the number of interstitial molecules in the water second coordination shell, in contradiction to suggestions that this phenomenon arises owing to hydrogen bond bending. Detailed analysis based upon two-dimensional distribution functions suggests an intimate link between the phenomenon of electrostriction and the behavior of water under high-pressure compression. We find the magnitude of the electrostrictive effect inferred from the neutron diffraction data to be greater than that found in the simulations. Investigation of the solvation structure suggests that the CHARMM force field overhydrates the terminal carboxy group, and that this overhydration is accompanied by the presence of bifurcated hydrogen bonds.

An overview of the management of morbid obesity.

Obesity is a modern-day epidemic with serious physical, psychological and economic implications for the patients. Tackling obesity is now a priority for most healthcare providers. Managing such patients can be complex, emotional, time consuming and often frustrating. Obesity surgery, in its various forms, has revolutionised this struggle. With appropriate selection of patients, adequate resources and a multidisciplinary team involvement, obesity can now effectively be "cured". It is vital that those who deal with obese patients know how to access these services and understand the processes involved in the journey from initial assessment to postoperative follow-up. Obesity surgery has a major impact in reducing obesity-related comorbidities such as diabetes and hypertension and contributes to society by returning patients to work. Prevention must be at the heart of any strategy to manage obesity, but, for established cases, surgery is taking centre stage and will continue to flourish as new techniques and procedures are developed.

Single-step doxorubicin-selected cancer cells overexpress the ABCG2 drug transporter through epigenetic changes.

Understanding the mechanisms of multidrug resistance (MDR) could improve clinical drug efficacy. Multidrug resistance is associated with ATP binding cassette (ABC) transporters, but the factors that regulate their expression at clinically relevant drug concentrations are poorly understood. We report that a single-step selection with low doses of anti-cancer agents, similar to concentrations reported in vivo, induces MDR that is mediated exclusively by ABCG2. We selected breast, ovarian and colon cancer cells (MCF-7, IGROV-1 and S-1) after exposure to 14 or 21 nM doxorubicin for only 10 days. We found that these cells overexpress ABCG2 at the mRNA and protein levels. RNA interference analysis confirmed that ABCG2 confers drug resistance. Furthermore, ABCG2 upregulation was facilitated by histone hyperacetylation due to weaker histone deacetylase 1-promoter association, indicating that these epigenetic changes elicit changes in ABCG2 gene expression. These studies indicate that the MDR phenotype arises following low-dose, single-step exposure to doxorubicin, and further suggest that ABCG2 may mediate early stages of MDR development. This is the first report to our knowledge of single-step, low-dose selection leading to overexpression of ABCG2 by epigenetic changes in multiple cancer cell lines.

p53 in signaling checkpoint arrest or apoptosis.

The cell cycle arrest and apoptotic functions of p53 both contribute to the role of this tumour suppressor protein in preventing replication of cells suffering DNA damage. Although the ability of p53 to function as a sequence-specific transcription factor appears to be directly and causally linked to the implementation of an arrest at the G1 stage of the cell cycle, the contribution of transcriptional activation to the apoptotic response is less clear. It seems likely that several p53 activities, both transcriptionally dependent and transcriptionally independent, can play a role in mediating cell death. The requirement for each of these functions appears to depend on the cell type, the cell environment and other genetic alterations already sustained by the cell in which p53 function is activated.

Imatinib mesylate and nilotinib (AMN107) exhibit high-affinity interaction with ABCG2 on primitive hematopoietic stem cells.

The majority of chronic phase chronic myeloid leukemia (CML) patients treated with the tyrosine kinase inhibitor (TKI) imatinib mesylate maintain durable responses to the drug. However, most patients relapse after withdrawal of imatinib and advanced stage patients often develop drug resistance. As CML is considered a hematopoietic stem cell cancer, it has been postulated that inherent protective mechanisms lead to relapse in patients. The ATP binding-cassette transporters ABCB1 (MDR-1; P-glycoprotein) and ABCG2 are highly expressed on primitive hematopoietic stem cells (HSCs) and have been shown to interact with TKIs. Herein we demonstrate a dose-dependent, reversible inhibition of ABCG2-mediated Hoechst 33342 dye efflux in primary human and murine HSC by both imatinib and nilotinib (AMN107), a novel aminopyrimidine inhibitor of BCR-ABL. ABCG2-transduced K562 cells were protected from imatinib and nilotinib-mediated cell death and from downregulation of P-CRKL. Moreover, photoaffinity labeling revealed interaction of both TKIs with ABCG2 at the substrate binding sites as they compete with the binding of [(125)I] IAAP and also stimulate the transporter's ATPase activity. Therefore, our evidence suggests for the role of ABC transporters in resistance to TKI on primitive HSCs and CML stem cells and provides a rationale how TKI resistance can be overcome in vivo.

Fourier transform infrared observation and density functional theory study of the AlC3 and AlC3Al linear chains trapped in solid Ar.

The vibrational spectra of linear AlC(3) and AlC(3)Al, formed by trapping the products of the dual laser evaporation of aluminum and carbon rods in solid Ar at approximately 10 K, were observed. Fourier transform infrared (FTIR) measurements of (13)C isotopic shifts are in good agreement with the predictions of density functional theory (DFT) B3LYP6-311+G(3df) calculations, enabling the first assignments of the nu(3)(sigma(u)) and nu(4)(sigma(u)) fundamentals of ((3)Sigma(g) (+)) linear AlC(3)Al at 1624.0 and 528.3 cm(-1), respectively, and the nu(2)(sigma) vibrational fundamental of ((2)Pi) linear AlC(3) at 1210.9 cm(-1).