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1.
J Med Genet ; 60(10): 987-992, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-36813544

RESUMO

Heterozygous germline pathogenic variants (GPVs) in SMARCA4, the gene encoding the ATP-dependent chromatin remodelling protein SMARCA4 (previously known as BRG1), predispose to several rare tumour types, including small cell carcinoma of the ovary, hypercalcaemic type, atypical teratoid and malignant rhabdoid tumour, and uterine sarcoma. The increase in germline testing of SMARCA4 in recent years has revealed putative GPVs affecting SMARCA4 in patients with other cancer types. Here we describe 11 patients with neuroblastoma (NBL), including 4 previously unreported cases, all of whom were found to harbour heterozygous germline variants in SMARCA4 Median age at diagnosis was 5 years (range 2 months-26 years); nine were male; and eight of nine cases had tumour location information in the adrenal gland. Eight of the germline variants were expected to result in loss of function of SMARCA4 (large deletion, truncating and canonical splice variants), while the remaining four were missense variants. Loss of heterozygosity of the wild-type SMARCA4 allele was found in all eight cases where somatic testing was performed, supporting the notion that SMARCA4 functions as a classic tumour suppressor. Altogether, these findings strongly suggest that NBL should be included in the spectrum of SMARCA4-associated tumours.


Assuntos
Carcinoma de Células Pequenas , Neuroblastoma , Feminino , Humanos , Lactente , Masculino , Biomarcadores Tumorais/genética , Carcinoma de Células Pequenas/diagnóstico , Carcinoma de Células Pequenas/genética , Carcinoma de Células Pequenas/patologia , DNA Helicases/genética , Mutação em Linhagem Germinativa/genética , Neuroblastoma/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Pré-Escolar , Criança , Adolescente , Adulto Jovem , Adulto
2.
J Med Genet ; 58(12): 853-858, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33168572

RESUMO

BACKGROUND: The strength of evidence supporting the validity of gene-disease relationships is variable. Hereditary cancer has the additional complexity of low or moderate penetrance for some confirmed disease-associated alleles. METHODS: To promote national consistency in interpretation of hereditary cancer/tumour gene test results, we requested opinions of representatives from Australian Family Cancer Clinics regarding the clinical utility of 157 genes initially collated for a national research project. Viewpoints were sought by initial survey, face-to-face workshop and follow-up survey. Subsequent review was undertaken by the eviQ Cancer Genetics Reference Committee, a national resource providing evidence-based and consensus-driven cancer treatment protocols. RESULTS: Genes were categorised by clinical actionability as: relevant for testing on presentation of common cancer/tumour types (n=45); relevant for testing in the context of specific rare phenotypes (n=74); insufficient clinical utility (n=34) or contentious clinical utility (n=3). Opinions for several genes altered during the study time frame, due to new information. CONCLUSION: Through an iterative process, consensus was achieved on genes with clinical utility for hereditary cancer/tumour conditions in the Australian setting. This study highlighted need for regular review of gene-disease lists, a role assumed in Australia for hereditary cancer/tumour predisposition genes by the eviQ Cancer Genetics Reference Committee.


Assuntos
Aconselhamento Genético/métodos , Predisposição Genética para Doença/genética , Testes Genéticos/métodos , Anotação de Sequência Molecular/métodos , Neoplasias/genética , Austrália , Consenso , Saúde da Família , Feminino , Estudos de Associação Genética/métodos , Mutação em Linhagem Germinativa , Humanos , Masculino , Oncologia/métodos , Neoplasias/diagnóstico , Linhagem , Proteínas Supressoras de Tumor/genética
3.
Hum Mutat ; 41(3): 641-654, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31769566

RESUMO

Visceral myopathy with abnormal intestinal and bladder peristalsis includes a clinical spectrum with megacystis-microcolon intestinal hypoperistalsis syndrome and chronic intestinal pseudo-obstruction. The vast majority of cases are caused by dominant variants in ACTG2; however, the overall genetic architecture of visceral myopathy has not been well-characterized. We ascertained 53 families, with visceral myopathy based on megacystis, functional bladder/gastrointestinal obstruction, or microcolon. A combination of targeted ACTG2 sequencing and exome sequencing was used. We report a molecular diagnostic rate of 64% (34/53), of which 97% (33/34) is attributed to ACTG2. Strikingly, missense mutations in five conserved arginine residues involving CpG dinucleotides accounted for 49% (26/53) of disease in the cohort. As a group, the ACTG2-negative cases had a more favorable clinical outcome and more restricted disease. Within the ACTG2-positive group, poor outcomes (characterized by total parenteral nutrition dependence, death, or transplantation) were invariably due to one of the arginine missense alleles. Analysis of specific residues suggests a severity spectrum of p.Arg178>p.Arg257>p.Arg40 along with other less-frequently reported sites p.Arg63 and p.Arg211. These results provide genotype-phenotype correlation for ACTG2-related disease and demonstrate the importance of arginine missense changes in visceral myopathy.


Assuntos
Actinas/genética , Substituição de Aminoácidos , Arginina , Estudos de Associação Genética , Predisposição Genética para Doença , Pseudo-Obstrução Intestinal/diagnóstico , Pseudo-Obstrução Intestinal/genética , Mutação , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Adulto , Colo/anormalidades , Análise Mutacional de DNA , Feminino , Genótipo , Humanos , Masculino , Técnicas de Diagnóstico Molecular , Fenótipo , Bexiga Urinária/anormalidades , Sequenciamento do Exoma , Adulto Jovem
5.
Langmuir ; 32(44): 11655-11663, 2016 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-27715063

RESUMO

Interactions between detergents and model membranes are well described by the three-stage model: saturation and solubilization boundaries divide bilayer-only, bilayer-micelle coexistence, and micelle-only ranges. An underlying assumption of the model is the equilibration of detergent between the two membrane leaflets. However, many detergents partition asymmetrically at room temperature due to slow flip-flop, such as sodium dodecyl sulfate (SDS) and lysolipids. In this work, we use isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) to investigate the solubilization of unilamellar POPC vesicles by 12:0 lysophosphocholine (12:0 LPC). Flip-flop of 12:0 LPC occurs beyond the time scale of our experiments, which establish a characteristic nonequilibrated state with asymmetric distribution: 12:0 LPC partitions primarily into the outer leaflet. Increasing asymmetry stress in the membrane does not lead to membrane failure, i.e., "cracking in" as seen for alkyl maltosides and other surfactants; instead, it reduces further membrane insertion which leads to the "staying out" of 12:0 LPC in solution. At above the critical micellar concentration of 12:0 LPC in the presence of the membrane, micelles persist and accommodate further LPC but take up lipid from vesicles only very slowly. Ultimately, solubilization proceeds via the micellar mechanism (Kragh-Hansen et al., 1995). With a combination of demicellization and solubilization experiments, we quantify the molar ratio partition coefficient (0.6 ± 0.1 mM-1) and enthalpy of partitioning (6.1 ± 0.3 kJ·mol-1) and estimate the maximum detergent/lipid ratio reached in the outer leaflet (<0.13). Despite the inapplicability of the three-stage model to 12:0 LPC at room temperature, we are able to extract quantitative information from ITC solubilization experiments and DLS that are important for the understanding of asymmetry-dependent processes such as endocytosis and the gating of mechanosensitive channels in vitro.

6.
Biochim Biophys Acta ; 1838(9): 2306-12, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24631665

RESUMO

The effective charge of membrane-active molecules such as the fungicidal lipopeptide surfactin (SF) is a crucial property governing solubility, membrane partitioning, and membrane permeability. We present zeta potential measurements of liposomes to measure the effective charge as well as membrane partitioning of SF by utilizing what we call an equi-activity analysis of several series of samples with different lipid concentrations. We observe an effective charge of -1.0 for SF at pH8.5 and insignificantly lower at pH7.4, illustrating that the effective charge may deviate strongly from the nominal value (-2 for 1 Asp, 1 Glu). The apparent partition coefficient decreases from roughly 100 to 20/mM with increasing membrane content of SF in agreement with the literature. Finally, by comparing zeta potentials measured soon after the addition of peptide to liposomes with those measured after a heat treatment to induce transmembrane equilibration of SF, we quantified the asymmetry of partitioning between the outer and inner leaflets. At very low concentration, SF binds exclusively to the outer leaflet. The onset of partial translocation to the inner leaflet occurs at about 5mol-% SF in the membrane. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.


Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Permeabilidade da Membrana Celular/efeitos dos fármacos , Lipopeptídeos/química , Peptídeos Cíclicos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Humanos , Bicamadas Lipídicas/química , Lipopeptídeos/farmacologia , Lipossomos/química , Potenciais da Membrana/efeitos dos fármacos , Peptídeos Cíclicos/farmacologia , Solubilidade
7.
Cancers (Basel) ; 15(20)2023 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-37894291

RESUMO

Germline pathogenic variants in the DNA mismatch repair (MMR) genes (Lynch syndrome) predispose to colorectal (CRC) and endometrial (EC) cancer. Lynch syndrome specific tumor features were evaluated for their ability to support the ACMG/InSiGHT framework in classifying variants of uncertain clinical significance (VUS) in the MMR genes. Twenty-eight CRC or EC tumors from 25 VUS carriers (6xMLH1, 9xMSH2, 6xMSH6, 4xPMS2), underwent targeted tumor sequencing for the presence of microsatellite instability/MMR-deficiency (MSI-H/dMMR) status and identification of a somatic MMR mutation (second hit). Immunohistochemical testing for the presence of dMMR crypts/glands in normal tissue was also performed. The ACMG/InSiGHT framework reclassified 7/25 (28%) VUS to likely pathogenic (LP), three (12%) to benign/likely benign, and 15 (60%) VUS remained unchanged. For the seven re-classified LP variants comprising nine tumors, tumor sequencing confirmed MSI-H/dMMR (8/9, 88.9%) and a second hit (7/9, 77.8%). Of these LP reclassified variants where normal tissue was available, the presence of a dMMR crypt/gland was found in 2/4 (50%). Furthermore, a dMMR endometrial gland in a carrier of an MSH2 exon 1-6 duplication provides further support for an upgrade of this VUS to LP. Our study confirmed that identifying these Lynch syndrome features can improve MMR variant classification, enabling optimal clinical care.

8.
Genome Med ; 15(1): 74, 2023 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-37723522

RESUMO

BACKGROUND: Many families and individuals do not meet criteria for a known hereditary cancer syndrome but display unusual clusters of cancers. These families may carry pathogenic variants in cancer predisposition genes and be at higher risk for developing cancer. METHODS: This multi-centre prospective study recruited 195 cancer-affected participants suspected to have a hereditary cancer syndrome for whom previous clinical targeted genetic testing was either not informative or not available. To identify pathogenic disease-causing variants explaining participant presentation, germline whole-genome sequencing (WGS) and a comprehensive cancer virtual gene panel analysis were undertaken. RESULTS: Pathogenic variants consistent with the presenting cancer(s) were identified in 5.1% (10/195) of participants and pathogenic variants considered secondary findings with potential risk management implications were identified in another 9.7% (19/195) of participants. Health economic analysis estimated the marginal cost per case with an actionable variant was significantly lower for upfront WGS with virtual panel ($8744AUD) compared to standard testing followed by WGS ($24,894AUD). Financial analysis suggests that national adoption of diagnostic WGS testing would require a ninefold increase in government annual expenditure compared to conventional testing. CONCLUSIONS: These findings make a case for replacing conventional testing with WGS to deliver clinically important benefits for cancer patients and families. The uptake of such an approach will depend on the perspectives of different payers on affordability.


Assuntos
Síndromes Neoplásicas Hereditárias , Humanos , Estudos Prospectivos , Oncogenes , Testes Genéticos , Células Germinativas
9.
Langmuir ; 28(40): 14129-36, 2012 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-22950856

RESUMO

Volumetric parameters have long been used to elucidate the phenomena governing the stability of protein structures, ligand binding, or transitions in macromolecular or colloidal systems. In spite of much success, many problems remain controversial. For example, hydrophobic groups have been discussed to condense adjacent water to a volume lower than that of bulk water, causing a negative contribution to the volume change of unfolding. However, expansivity data were interpreted in terms of a structure-making effect that expands the water interacting with the solute. We have studied volume and expansivity effects of transfer of alkyl chains into micelles by pressure perturbation calorimetry and isothermal titration calorimetry. For a series of alkyl maltosides and glucosides, the methylene group contribution to expansivity was obtained as 5 uL/(mol K) in a micelle (mimicking bulk hydrocarbon) but 27 uL/(mol K) in water (20 °C). The latter value is virtually independent of temperature and similar to that obtained from hydrophobic amino acids. Methylene contributions of micellization are about -60 J/(mol K) to heat capacity and 2.7 mL/mol to volume. Our data oppose the widely accepted assumption that water-exposed hydrophobic groups yield a negative contribution to expansivity at low temperature that would imply a structure-making, water-expanding effect.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Micelas , Temperatura , Aminoácidos/química , Calorimetria , Tensoativos/química
10.
Nanoscale Adv ; 4(23): 5109-5122, 2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36504745

RESUMO

Both antimicrobial peptides and their synthetic mimics are potential alternatives to classical antibiotics. They can induce several membrane perturbations including permeabilization. Especially in model studies, aggregation of vesicles by such polycations is often reported. Here, we show that unintended vesicle aggregation or indeed fusion can cause apparent leakage in model studies that is not possible in most microbes, thus potentially leading to misinterpretations. The interactions of a highly charged and highly selective membrane-active polycation with negatively charged phosphatidylethanolamine/phosphatidylglycerol (PE/PG) vesicles are studied by a combination of biophysical methods. At low polycation concentrations, apparent vesicle aggregation was found to involve exchange of lipids. Upon neutralization of the negatively charged vesicles by the polycation, full fusion and leakage occurred and leaky fusion is suspected. To elucidate the interplay of leakage and fusion, we prevented membrane contacts by decorating the vesicles with PEG-chains. This inhibited fusion and also leakage activity. Leaky fusion is further corroborated by increased leakage with increasing likeliness of vesicle-vesicle contacts. Because of its similar appearance to other leakage mechanisms, leaky fusion is difficult to identify and might be overlooked and more common amongst polycationic membrane-active compounds. Regarding biological activity, leaky fusion needs to be carefully distinguished from other membrane permeabilization mechanisms, as it may be less relevant to bacteria, but potentially relevant for fungi. Furthermore, leaky fusion is an interesting effect that could help in endosomal escape for drug delivery. A comprehensive step-by-step protocol for membrane permeabilization/vesicle leakage using calcein fluorescence lifetime is provided in the ESI.

11.
Fam Cancer ; 21(2): 157-166, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-33970363

RESUMO

The increasing use of genetic testing for BRCA1/2 and other pathogenic variants in the management of women with breast and ovarian cancer necessitates increased genetic literacy in oncology healthcare professionals. This pilot study aimed to evaluate an online training program to increase genetic literacy and communication skills in Australian oncology healthcare professionals tasked with discussing and coordinating mainstream genetic testing with breast and ovarian cancer patients. A training website with embedded videos was developed. This study assesses the website's acceptability and user-friendliness; suggestions for improvement were also elicited. Oncology healthcare professionals were recruited through relevant professional organisations, invited to the study by email, asked to work through the website and then complete an online questionnaire. Thirty-two oncology healthcare professionals completed the questionnaire after viewing the website. Nearly all participants were satisfied with the information contained in the program (very satisfied: n = 14/32, 44%, satisfied: n = 17/32, 53%, neither satisfied nor dissatisfied: n = 1/32, 3%) and reported that they had gained new skills (n = 29/32, 91%) and had increased confidence (n = 29/31, 94%) in communicating with breast and ovarian cancer patients about genetic testing. More than 93% (28/30) of participants endorsed the online program as clearly presented, informative, relevant and useful. This pilot study demonstrated high feasibility and acceptability of the training program to increase genetic literacy and communication skills in oncology healthcare professionals discussing genetic testing with breast and ovarian cancer patients. Further evidence from a randomised trial is needed to evaluate effects on changing clinical practice, improving patient outcomes, and cost-effectiveness.


Assuntos
Proteína BRCA2/genética , Alfabetização , Neoplasias Ovarianas , Austrália , Proteína BRCA1/genética , Carcinoma Epitelial do Ovário/genética , Comunicação , Atenção à Saúde , Feminino , Testes Genéticos , Humanos , Neoplasias Ovarianas/genética , Projetos Piloto
12.
Biochemistry ; 50(7): 1226-37, 2011 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-21214273

RESUMO

Photocontrolled transcription factors could be powerful tools for probing the roles of transcriptional processes in a variety of settings. Previously, we designed a photocontrolled DNA-binding protein based on a fusion between the bZIP region of GCN4 and photoactive yellow protein from Halorhodospira halophila [Morgan, S. A., et al. (2010) J. Mol. Biol. 399, 94-112]. Here we report a structure-based attempt to improve the degree of photoswitching observed with this chimeric protein. Using computational design tools PoPMuSiC 2.0, Rosetta, Eris, and bCIPA, we identified a series of single- and multiple-point mutations that were expected to stabilize the folded dark state of the protein and thereby enhance the degree of photoswitching. While a number of these mutations, particularly those that introduced a hydrophobic residue at position 143, did significantly enhance dark-state protein stability as judged by urea denaturation studies, dark-state stability did not correlate directly with the degree of photoswitching. Instead, the influence of mutations on the degree of photoswitching was found to be related to their effects on the degree to which DNA binding slowed the pB to pG transition in the PYP photocycle. One mutant, K143F, caused an ∼10-fold slowing of the photocycle and also showed the largest difference in the apparent K(d) for DNA binding, 3.5-fold lower, upon irradiation. This change in the apparent K(d) causes a 12-fold enhancement in the fraction bound DNA upon irradiation due to the cooperativity of DNA binding by this family of proteins. The results highlight the strengths and weaknesses of current approaches to a practical problem in protein design and suggest strategies for further improvement of designed photocontrolled transcription factors.


Assuntos
Proteínas de Ligação a DNA/síntese química , Luz , Proteínas Luminescentes/síntese química , Engenharia de Proteínas/métodos , Sequência de Aminoácidos , Cristalografia por Raios X , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Halorhodospira halophila/genética , Halorhodospira halophila/metabolismo , Proteínas Luminescentes/genética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida/métodos , Processos Fotoquímicos , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína/genética , Proteínas Recombinantes/síntese química , Proteínas Recombinantes/genética
13.
J Am Chem Soc ; 133(12): 4518-26, 2011 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-21370889

RESUMO

Oligodeoxyribonucleotides (ODN) with repeats of the human telomeric sequence can adopt different tetrahelical conformations that exhibit similar energetic parameters. We studied the volumetric properties of the folded and unfolded states of an ODN with four repeats of the human telomeric sequence, d[A(GGGTTA)(3)GGG], by combining pressure-perturbation calorimetry (PPC), vibrating tube densimetry, ultrasonic velocimetry, and UV melting under high pressure. We carried out our volumetric measurements in aqueous buffers at pH 7 containing 20, 50, and 100 mM NaCl. All of the methods employed yielded volumetric parameters that were in excellent agreement. The molar volume changes, ΔV, of the conformational transition leading to formation of the folded state are large and positive. At 50 mM NaCl, the average transition volume, ΔV(tr), obtained from all the methods is 56.4 ± 3.5 cm(3) mol(-1) at the transition temperature of 47 °C, with ΔV(tr) decreasing with an increase in temperature. We carried out a molecular dynamics simulation of the change in the intrinsic geometric parameters of the ODN accompanying quadruplex formation. On the basis of the experimental and computational results, the folding transition of the ODN is accompanied by a release of 103 ± 44 water molecules from its hydration shell to the bulk. This number corresponds to ~18% of the net hydration of the coil conformation.


Assuntos
Quadruplex G , Oligodesoxirribonucleotídeos/química , Cloreto de Sódio/química , Eletroquímica , Humanos , Modelos Moleculares
14.
Mol Phylogenet Evol ; 59(2): 354-63, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21397706

RESUMO

Development of methods for estimating species trees from multilocus data is a current challenge in evolutionary biology. We propose a method for estimating the species tree topology and branch lengths using approximate Bayesian computation (ABC). The method takes as data a sample of observed rooted gene tree topologies, and then iterates through the following sequence of steps: First, a randomly selected species tree is used to compute the distribution of rooted gene tree topologies. This distribution is then compared to the observed gene topology frequencies, and if the fit between the observed and the predicted distributions is close enough, the proposed species tree is retained. Repeating this many times leads to a collection of retained species trees that are then used to form the estimate of the overall species tree. We test the performance of the method, which we call ST-ABC, using both simulated and empirical data. The simulation study examines both symmetric and asymmetric species trees over a range of branch lengths and sample sizes. The results from the simulation study show that the model performs very well, giving accurate estimates for both the topology and the branch lengths across the conditions studied, and that a sample size of 25 loci appears to be adequate for the method. Further, we apply the method to two empirical cases: a 4-taxon data set for primates and a 7-taxon data set for yeast. In both cases, we find that estimates obtained with ST-ABC agree with previous studies. The method provides efficient estimation of the species tree, and does not require sequence data, but rather the observed distribution of rooted gene topologies without branch lengths. Therefore, this method is a useful alternative to other currently available methods for species tree estimation.


Assuntos
Algoritmos , Teorema de Bayes , Classificação/métodos , Modelos Genéticos , Filogenia , Animais , Simulação por Computador , Humanos , Primatas/genética , Leveduras
15.
Langmuir ; 27(5): 1693-9, 2011 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-21226468

RESUMO

We present the application of pressure perturbation calorimetry (PPC) as a new method for the volumetric characterization of the micelle formation of surfactants. The evaluation is realized by a global fit of PPC curves at different surfactant concentration ranging, if possible, from below to far above the CMC. It is based on the knowledge of the temperature dependence of the CMC, which can for example be characterized by isothermal titration calorimetry. We demonstrate the new approach for decyl-ß-maltopyranoside (DM). It shows a strong volume increase upon micelle formation of 16 ± 2.5 mL/mol (+4%) at 25 °C, and changes with temperature by -0.1 mL/(mol K). The apparent molar expansivity (E(S)) decreases upon micelle formation from 0.44 to 0.31 mL/(mol K) at 25 °C. Surprisingly, the temperature dependence of the expansivity of DM in solution (as compared with that of maltose) does not agree with the principal behavior described for polar (E(S)(T) decreasing) and hydrophobic (E(S)(T) increasing) solutes or moieties before. The results are discussed in terms of changes in hydration of the molecules and internal packing of the micelles and compared with the volumetric effects of transitions of proteins, DNA, lipids, and polymers.


Assuntos
Calorimetria , Micelas , Pressão , Interações Hidrofóbicas e Hidrofílicas , Maltose/análogos & derivados , Maltose/química , Tensoativos/química
17.
J Colloid Interface Sci ; 504: 283-293, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28551523

RESUMO

Digitonin is commonly used to permeabilize cell membranes and solubilize membrane components. It interacts specifically with cholesterol in the membrane which leads to the formation of pores. Thus far, the mechanism by which digitonin interacts with the membrane has only been described qualitatively. We investigated this interaction in model membranes that contain little or no cholesterol with a combination of isothermal titration calorimetry, dynamic light scattering, and zeta potential measurements. Digitonin partitions fully asymmetrically into large unilamellar vesicles of phosphocholine (PC) lipid at 20°C (remaining in the outer leaflet only), with a partition coefficient of 0.22±0.04mM-1 and ΔH of partitioning of 23.3±1.6kJmol-1. Beyond a digitonin/lipid ratio of ∼0.1 in the outer leaflet, digitonin micelles coexist with vesicles without solubilizing them-even at high digitonin concentrations. This "staying out" of digitonin was also observed with phosphoserine (PS), PC/PS, and PC/PS/cholesterol vesicles. The mechanism by which digitonin perturbs and solubilizes the membrane is very different when the membrane contains little or no cholesterol as opposed to 20-30mol% cholesterol. The role of digitonin should thus be carefully considered in the design of preparative protocols and experiments in studies of cellular processes and membrane proteins.


Assuntos
Colesterol/química , Digitonina/química , Lipossomos/química , Fosfatidilcolinas/química , Fosfatidilserinas/química , Bicamadas Lipídicas/química , Micelas , Termodinâmica
18.
J Clin Oncol ; 23(31): 8025-32, 2005 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-16258100

RESUMO

PURPOSE: We previously evaluated fatigue, menopausal symptoms, and cognitive dysfunction in patients receiving adjuvant therapy for breast cancer and matched healthy women. Here we report assessment of these women 1 and 2 years later. PATIENTS AND METHODS: Patients without relapse and controls were evaluated by the Functional Assessment of Cancer Treatment-General Quality of Life questionnaire, with subscales for fatigue and endocrine symptoms, and by the High Sensitivity Cognitive Screen. RESULTS: There were 104, 91, and 83 patients and 102, 81, and 81 controls assessed at baseline and at 1 and 2 years, respectively. Median Functional Assessment of Cancer Treatment-Fatigue scores (range, 0 to 52) for patients improved from 31 (on chemotherapy) to 43 and 45 at 1 and 2 years, respectively, but were stable in controls (46 to 48). Median Functional Assessment of Cancer Treatment-Endocrine Symptoms scores (range, 0 to 72) for patients improved from 57 (on chemotherapy) to 59 and 61 at 1 and 2 years, respectively, and were stable in controls (64 to 65). Differences between patients and controls remained significant for these scales. The incidence of moderate-severe cognitive dysfunction by the High Sensitivity Cognitive Screen decreased in patients from 16% (on chemotherapy) to 4.4% and 3.8% and in controls from 5% to 3.6% and 0% at 1 and 2 years, respectively. There were minimal differences between estrogen receptor-positive patients who started hormonal therapy (mainly tamoxifen) after chemotherapy and estrogen receptor-negative patients who did not. Differences in quality of life between patients and controls were significant only at baseline. CONCLUSION: Fatigue, menopausal symptoms, and cognitive dysfunction are important adverse effects of chemotherapy that improve in most patients. Hormonal treatment has minimal impact on them.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias da Mama/tratamento farmacológico , Transtornos Cognitivos/induzido quimicamente , Fadiga/induzido quimicamente , Menopausa/efeitos dos fármacos , Neoplasias da Mama/psicologia , Estudos de Casos e Controles , Quimioterapia Adjuvante , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos Prospectivos , Qualidade de Vida , Fatores de Risco , Inquéritos e Questionários
19.
Asia Pac J Clin Oncol ; 12(2): e222-8, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24571381

RESUMO

AIMS: Perioperative chemotherapy has improved the prognosis for patients with operable osteosarcoma. The literature is conflicting about which regimen is optimal. The aim of this study was to evaluate the survival outcomes of two cohorts of patients with operable osteosarcoma treated with different perioperative chemotherapy regimens. METHODS: This was a retrospective review of patients diagnosed with operable osteosarcoma treated at the Princess Alexandra Hospital from 1986 to 2009. The standard perioperative chemotherapy regimen changed from the modified T10 Rosen protocol to cisplatin/doxorubicin in 1997. Using the Kaplan-Meier method, overall survival (OS) and disease-free survival (DFS) curves were generated for the cisplatin/doxorubicin and the modified T10 Rosen cohorts. RESULTS: Seventy-one patients were identified of whom 63 had potentially curable disease. Of these, 24 received the modified T10 Rosen regimen and 39 received cisplatin/doxorubicin. There was a non-significant trend toward better OS and DFS in the patients who received the modified T10 Rosen protocol. CONCLUSION: The trend toward poorer survival in the cisplatin/doxorubicin cohort, in combination with current evidence, has prompted our institution to change its practice.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/cirurgia , Osteossarcoma/tratamento farmacológico , Osteossarcoma/cirurgia , Adolescente , Adulto , Idoso , Quimioterapia Adjuvante , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Assistência Perioperatória/métodos , Prognóstico , Estudos Retrospectivos , Adulto Jovem
20.
Adv Healthc Mater ; 4(17): 2709-18, 2015 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-26474414

RESUMO

Most drug delivery systems have been developed for efficient delivery to tumor sites via targeting and on-demand strategies, but the carriers rarely execute synergistic therapeutic actions. In this work, C8, a cationic, pH-triggered anticancer peptide, is developed by incorporating histidine-mediated pH-sensitivity, amphipathic helix, and amino acid pairing self-assembly design. We designed C8 to function as a pH-responsive nanostructure whose cytotoxicity can be switched on and off by its self-assembly: Noncytotoxic ß-sheet fibers at high pH with neutral histidines, and positively charged monomers with membrane lytic activity at low pH. The selective activity of C8, tested for three different cancer cell lines and two noncancerous cell lines, is shown. Based on liposome leakage assays and multiscale computer simulations, its physical mechanisms of pore-forming action and selectivity are proposed, which originate from differences in the lipid composition of the cellular membrane and changes in hydrogen bonding. C8 is then investigated for its potential as a drug carrier. C8 forms a nanocomplex with ellipticine, a nonselective model anticancer drug. It selectively targets cancer cells in a pH-responsive manner, demonstrating enhanced efficacy and selectivity. This study provides a novel powerful strategy for the design and development of multifunctional self-assembling peptides for therapeutic and drug delivery applications.


Assuntos
Antineoplásicos/química , Peptídeos/química , Animais , Linhagem Celular Tumoral , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Elipticinas/química , Histidina/química , Humanos , Concentração de Íons de Hidrogênio , Lipossomos/química , Camundongos , Células NIH 3T3 , Nanoestruturas/química
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