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1.
N Engl J Med ; 388(22): 2058-2070, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-37256976

RESUMO

BACKGROUND: AKT pathway activation is implicated in endocrine-therapy resistance. Data on the efficacy and safety of the AKT inhibitor capivasertib, as an addition to fulvestrant therapy, in patients with hormone receptor-positive advanced breast cancer are limited. METHODS: In a phase 3, randomized, double-blind trial, we enrolled eligible pre-, peri-, and postmenopausal women and men with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer who had had a relapse or disease progression during or after treatment with an aromatase inhibitor, with or without previous cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor therapy. Patients were randomly assigned in a 1:1 ratio to receive capivasertib plus fulvestrant or placebo plus fulvestrant. The dual primary end point was investigator-assessed progression-free survival assessed both in the overall population and among patients with AKT pathway-altered (PIK3CA, AKT1, or PTEN) tumors. Safety was assessed. RESULTS: Overall, 708 patients underwent randomization; 289 patients (40.8%) had AKT pathway alterations, and 489 (69.1%) had received a CDK4/6 inhibitor previously for advanced breast cancer. In the overall population, the median progression-free survival was 7.2 months in the capivasertib-fulvestrant group, as compared with 3.6 months in the placebo-fulvestrant group (hazard ratio for progression or death, 0.60; 95% confidence interval [CI], 0.51 to 0.71; P<0.001). In the AKT pathway-altered population, the median progression-free survival was 7.3 months in the capivasertib-fulvestrant group, as compared with 3.1 months in the placebo-fulvestrant group (hazard ratio, 0.50; 95% CI, 0.38 to 0.65; P<0.001). The most frequent adverse events of grade 3 or higher in patients receiving capivasertib-fulvestrant were rash (in 12.1% of patients, vs. in 0.3% of those receiving placebo-fulvestrant) and diarrhea (in 9.3% vs. 0.3%). Adverse events leading to discontinuation were reported in 13.0% of the patients receiving capivasertib and in 2.3% of those receiving placebo. CONCLUSIONS: Capivasertib-fulvestrant therapy resulted in significantly longer progression-free survival than treatment with fulvestrant alone among patients with hormone receptor-positive advanced breast cancer whose disease had progressed during or after previous aromatase inhibitor therapy with or without a CDK4/6 inhibitor. (Funded by AstraZeneca and the National Cancer Institute; CAPItello-291 ClinicalTrials.gov number, NCT04305496.).


Assuntos
Inibidores da Aromatase , Neoplasias da Mama , Feminino , Humanos , Masculino , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Inibidores da Aromatase/efeitos adversos , Inibidores da Aromatase/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Método Duplo-Cego , Fulvestranto/efeitos adversos , Fulvestranto/uso terapêutico , Recidiva Local de Neoplasia/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt , Receptor ErbB-2
2.
Lancet Oncol ; 25(9): 1231-1244, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39214106

RESUMO

BACKGROUND: CAPItello-291 is an ongoing phase 3 trial in which capivasertib-fulvestrant significantly improved progression-free survival versus placebo-fulvestrant in patients with hormone receptor-positive, HER2-negative advanced breast cancer who had relapse or disease progression during or after aromatase inhibitor treatment, in both the overall population and in patients with PIK3CA, AKT1, or PTEN-altered tumours. This study further explored patient-reported health-related quality of life (HRQOL), functioning, symptoms, and symptom tolerability in CAPItello-291. METHODS: This phase 3, randomised, double-blind, placebo-controlled trial, which was conducted across 193 hospitals and cancer centres in 19 countries, enrolled women with any menopausal status or men, aged ≥18 years (≥20 years in Japan), with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer who had relapse or disease progression during or after treatment with an aromatase inhibitor, with or without previous cyclin-dependent kinase (CDK) 4 or 6 inhibitor therapy. Patients had an Eastern Cooperative Oncology Group/WHO performance score of 0 or 1 and could have received up to two previous lines of endocrine therapy and up to one previous line of chemotherapy for advanced disease. Patients were randomly assigned (1:1) using block randomisation (stratified according to the presence or absence of liver metastases, previous use of a CDK4/6 inhibitor [yes vs no], and geographical region) to receive oral capivasertib 400 mg (twice daily for 4 days, followed by 3 days off) plus intramuscular fulvestrant 500 mg (every 14 days for the first three injections, then every 28 days) or placebo with matching fulvestrant dosing. The dual primary endpoint of the trial was investigator-assessed progression-free survival assessed both in the overall population and among patients with PIK3CA, AKT1, or PTEN-altered tumours. The EORTC Quality of Life Questionnaire 30-item core module (QLQ-C30) and breast module (QLQ-BR23), Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), and Patient Global Impression of Treatment Tolerability (PGI-TT) questionnaires were used to assess patient-reported outcomes. Evaluation of EORTC QLQ-C30 and EORTC QLQ-BR23 were secondary endpoints and evaluation of PRO-CTCAE and PGI-TT were pre-defined exploratory endpoints, and these endpoints are the subject of analysis in this Article. Data were collected at baseline and prespecified timepoints. Patient-reported outcomes were analysed in all randomly assigned patients with an evaluable baseline assessment and at least one evaluable post-baseline assessment. Change from baseline was assessed using mixed model with repeated measures for EORTC QLQ-C30 and summarised for QLQ-BR23. Time to deterioration was described using the Kaplan-Meier method. PGI-TT and PRO-CTCAE responses were summarised at each treatment cycle. Patient-reported outcomes were not prospectively powered for statistical comparison. The trial is registered with ClinicalTrials.gov, NCT04305496. FINDINGS: Between June 2, 2020, and Oct 13, 2021, 901 patients were enrolled, of whom 708 patients were randomly assigned to receive capivasertib-fulvestrant (n=355) or placebo-fulvestrant (n=353). The median age of the patients was 59 years (IQR 51-67) in the capivasertib-fulvestrant group and 58 years (IQR 49-66) in the placebo-fulvestrant group. At data cutoff (Aug 15, 2022), the median duration of follow-up for progression-free survival in censored patients was 13·0 months (IQR 9·1-16·7) for capivasertib-fulvestrant and 12·7 months (IQR 2·0-16·4) for placebo-fulvestrant in the overall population. EORTC QLQ-C30 global health status/quality of life (GHS/QOL) scores were maintained from baseline and were similar between treatment groups throughout the study period (difference in mean change from baseline of -2·5 [95% CI -4·5 to -0·6] with capivasertib-fulvestrant vs -5·6 [-7·9 to -3·4] with placebo-fulvestrant; treatment difference 3·1 [95% CI 0·2 to 6·0]). Median time to deterioration in EORTC QLQ-C30 GHS/QOL was 24·9 months (95% CI 13·8 to not reached) in the capivasertib-fulvestrant group and 12·0 months (10·2 to 15·7) in the placebo-fulvestrant group (hazard ratio [HR] 0·70, 95% CI 0·53 to 0·92). Time to deterioration HRs for all EORTC QLQ-C30 and QLQ-BR23 subscale scores showed little difference between the treatment groups, except for diarrhoea, which was worse in the capivasertib-fulvestrant group than in the placebo-fulvestrant group (HR 2·75, 95% CI 2·01-3·81). In PRO-CTCAE symptom assessment, the proportion of patients reporting loose and watery stools "frequently" or "almost constantly" was 29% higher at cycle 1, day 15 in the capivasertib-fulvestrant group than in the placebo-fulvestrant group, decreasing at subsequent cycles. Other PRO-CTCAE-reported symptoms (rash, mouth or throat sores, itchy skin, and numbness or tingling in hands or feet) were absent or mild in most patients in both groups throughout treatment. According to the PGI-TT, most patients in both groups reported "not at all" or "a little bit" of bother from treatment side-effects. INTERPRETATION: Patient-reported outcomes from CAPItello-291 demonstrated that capivasertib-fulvestrant delayed time to deterioration of GHS/QOL and maintained other dimensions of HRQOL (except symptoms of diarrhoea) similarly to fulvestrant. With the clinical efficacy and manageable safety profile, these exploratory results further support the positive benefit-risk profile of capivasertib-fulvestrant in this population. FUNDING: AstraZeneca.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica , Neoplasias da Mama , Fulvestranto , Medidas de Resultados Relatados pelo Paciente , Pirimidinas , Qualidade de Vida , Receptor ErbB-2 , Receptores de Estrogênio , Receptores de Progesterona , Humanos , Feminino , Fulvestranto/uso terapêutico , Fulvestranto/administração & dosagem , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Método Duplo-Cego , Receptor ErbB-2/metabolismo , Pessoa de Meia-Idade , Receptores de Estrogênio/metabolismo , Idoso , Receptores de Progesterona/metabolismo , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Pirimidinas/administração & dosagem , Pirimidinas/uso terapêutico , Intervalo Livre de Progressão , Adulto , Pirrolidinas/administração & dosagem , Pirrolidinas/uso terapêutico , Pirróis
3.
Int J Mol Sci ; 24(9)2023 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-37175647

RESUMO

More than 275 million people in the world are carriers of a heterozygous mutation of the CFTR gene, associated with cystic fibrosis, the most common autosomal recessive disease among Caucasians. Some recent studies assessed the association between carriers of CFTR variants and some pathologies, including cancer risk. The aim of this study is to analyze the landscape of germline pathogenic heterozygous CFTR variants in patients with diagnosed malignant neoplasms. For the first time in Russia, we evaluated the frequency of CFTR pathogenic variants by whole-genome sequencing in 1800 patients with cancer and compared this with frequencies of CFTR variants in the control group (1825 people) adjusted for age and 10,000 healthy individuals. In the issue, 47 out of 1800 patients (2.6%) were carriers of CFTR pathogenic genetic variants: 0.028 (42/1525) (2.8%) among breast cancer patients, 0.017 (3/181) (1.7%) among colorectal cancer patients and 0.021 (2/94) (2.1%) among ovarian cancer patients. Pathogenic CFTR variants were found in 52/1825 cases (2.85%) in the control group and 221 (2.21%) in 10,000 healthy individuals. Based on the results of the comparison, there was no significant difference in the frequency and distribution of pathogenic variants of the CFTR gene, which is probably due to the study limitations. Obviously, additional studies are needed to assess the clinical significance of the heterozygous carriage of CFTR pathogenic variants in the development of various pathologies in the future, particularly cancer.


Assuntos
Neoplasias da Mama , Regulador de Condutância Transmembrana em Fibrose Cística , Humanos , Feminino , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Predisposição Genética para Doença , Mutação , Células Germinativas
4.
Artigo em Inglês | MEDLINE | ID: mdl-38317747

RESUMO

Background: The role of cytoreductive surgery for patients with recurrent or metastatic gastrointestinal stromal tumors (mGISTs) responding to imatinib (IM) has not yet been established. We carried out a retrospective analysis of the outcomes of patients with mGISTs in two Russian cancer centers. We compared two cohorts: treated (Group S) or not treated with surgery (Group NS) after a partial response (PR) or stable disease (SD) while on IM. Methods: A total 44 patients treated by IM as first line treatment were included in our analysis. Prognostically similar patients only sensitive to IM cases with hepatic or peritoneal metastases as well as durable response to IM lasting more than 12 months were included in a control arm. Patients in Group NS received only IM until disease progression. Patients in Group S were treated additionally with metastasectomy after having response or SD on IM. Results: The baseline characteristics were similar between the groups with several trends: a higher proportion of patients achieved a PR in Group S (87% vs. 55%, P=0.165), and greater number of patients had peritoneal metastases in Group NS (45% vs. 27%, P=0.759). The median time to surgery from the initiation of IM was 8 months. Progression-free survival (PFS) and overall survival (OS) were significantly longer in Group S than Group NS: the median PFS was 78 vs. 35 months (P=0.088); the median OS was 141 vs. 80 months (P=0.154). Conclusions: The surgical resection of residual lesions after disease control with IM is likely to be beneficial to patients with mGISTs.

5.
Front Oncol ; 14: 1401910, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39132502

RESUMO

Background: Breast cancer (BC) mortality primarily stems from metastases rather than the primary tumor itself. Perioperative stress, encompassing both surgical and anesthetic factors, profoundly impacts the immune system, leading to alterations in neuroendocrine pathways and immune functions, potentially facilitating tumor progression and metastasis. Understanding the immunomodulatory effects of different anesthesia techniques is crucial for optimizing perioperative care in patients with BC. The neutrophil-to-lymphocyte ratio (NLR) serves as one of the key indicators of perioperative immune response. Objective: To compare the effects of inhalation anesthesia (IA) and total intravenous anesthesia (TIVA) on perioperative immune response in BC surgery patients. Methods: In this randomized, double-blind clinical trial, BC surgery patients were randomized to receive either TIVA with propofol or IA with sevoflurane. The primary endpoint was NLR assessment. Secondary immune parameters measured included natural killer cells, various T cell subsets, B cells, the immuno-regulatory index [T-helpers (CD3+CD4+)/cytotoxic T-cells (CD3+CD8+)], matrix metallopeptidases (MMP-9), complement components, and immunoglobulins, preoperatively and at 1 and 24 hours postoperatively. Results: The study included 98 patients (IA: 48, TIVA: 50). The baseline characteristics exhibited remarkable similarity across the groups. No significant difference in absolute NLR values was found between IA and TIVA groups at any time point (1 hour: p = 0.519, 24 hours: p = 0.333). Decreased IgA and IgM levels post-surgery suggested potential negative impacts of IA on humoral immunity compared to TIVA. CRP levels increased more by 24 hours (p = 0.044) in IA compared to TIVA. No significant differences were observed in natural killer cells, T cell subsets, B cells, MMP-9 levels or complement components between groups. Significant differences in the immuno-regulatory index between the TIVA and IA groups at one hour postoperatively (p = 0.033) were not maintained at 24 hours. Conclusion: While there were no notable differences in NLR among the types of anesthesia, the observed disparities in immunoglobulin content and C-reactive protein levels between groups suggest that we cannot dismiss the potential immunosuppressive effects of inhalational anesthesia in breast cancer surgeries. Further investigation needed to clarify the impact of various anesthesia methods on immune function and their implications for long-term cancer outcomes.

6.
World J Clin Oncol ; 14(3): 131-137, 2023 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-37009526

RESUMO

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of gastrointestinal tract. The most common sites of metastases are the liver and the peritoneum, whereas breast metastases from GIST are extremely rare. We present a second case of GIST breast metastasis. CASE SUMMARY: We found a case of breast metastasis from rectum GIST. A 55-year-old female patient presented with rectum tumor with multiply liver lesions and metastasis in the right breast. Abdominal-perineal extirpation of rectum was performed, histology and immunohistochemistry study showed GIST, mixed type with CD117 and DOG-1 positive staining. The patient was taking imatinib 400 mg for 22 mo with stable disease. Because of growth of the breast metastasis the treatment was changed twice: The dose of imatinib was doubled with further progression in the breast lesion and then the patient was receiving sunitinib for 26 mo with partial response in the right breast and stable disease in the liver lesions. The breast lesion increased and right breast resection was done - surgery on local progression, the liver metastases were stable. Histology and immunohistochemistry studies revealed GIST metastasis, CD 117 and DOG 1 positive with KIT exon 11 mutation. After surgery the patient resumed imatinib. Until now the patient has been taking imatinib 400 mg for 19 mo without progression, last follow up was in November 2022. CONCLUSION: GISTs breast metastases are extremely rare, we described the second case. At the same time second primary tumors have been reported frequently in patients diagnosed with GISTs and breast cancer is one of the most common second primary tumors in patients with GISTs. That is why it is very important to distinguish primary from metastatic breast lesions. Surgery on local progression made it possible to resume less toxic treatment.

7.
Biomed Rep ; 16(6): 46, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35620307

RESUMO

Anti-angiogenic anticancer drugs that block vascular endothelial growth factor (VEGF) can cause kidney damage. An early assessment of the risk of nephrotoxicity would allow the development of optimal treatment approaches and allow for relatively safer therapeutic regimens. The aim of this study was to assess the utility of neutrophilic gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), hypoxia inducible factor-1α (HIF-1α) and nephrin levels in urine as early biomarkers for the nephrotoxicity of anti-VEGF drugs. The study included 50 patients who received anti-VEGF drugs (aflibercept, bevacizumab or ramucirumab) for 8 weeks. The levels of KIM-1, NGAL, HIF-1α and nephrin in urine samples were determined by ELISA before treatment and after 1, 2, 4 and 8 weeks of treatment. To assess risk factors for nephrotoxicity, a logistic regression analysis was performed with the inclusion of the primary clinical and laboratory parameters. The primary outcome measure was a decrease in glomerular filtration rate (GFR) to <60 ml/min/1.73 m2 at 8 weeks, and nephrotoxicity resulting in discontinuation within 9 months. The primary outcome goal was achieved in 21 (42%) patients treated with anti-VEGF drugs. Increased NGAL, KIM-1, HIF-1α and nephrin levels in urine at 1 week of treatment predicted the development of nephrotoxicity. High sensitivity and specificity of these urinary biomarkers were established by ROC analysis: KIM-1 [area under the curve (AUC) 0.69], NGAL (AUC 0.7), HIF-1α (AUC 0.7) and nephrin (AUC 0.7). The unfavorable predictors of nephrotoxicity were an initial decrease in estimated GFR, a history of arterial hypertension, and an increase in urinary concentration KIM-1 OR of 1.1 [CI 95% 1.02-1.183], and HIF-1α OR of 5.6 [CI 95% 3.601-8.949] (P<0,05) at 1 and 2 weeks of treatment. Urinary NGAL, KIM-1, HIF-1α and nephrin are early biomarkers of nephrotoxicity following treatment with anti-VEGF anticancer drugs. The independent risk factors for nephrotoxicity are the initial decrease in GFR, arterial hypertension, and an increase in the concentration of KIM-1 and HIF-1α in the urine in the early stages of therapy.

8.
Clin Breast Cancer ; 22(3): 223-234, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34844889

RESUMO

Endocrine therapy (ET) for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR-positive/HER2-negative) metastatic breast cancer (MBC) has changed markedly over recent years with the emergence of new ETs and the use of molecularly targeted agents. Cytotoxic chemotherapy continues, however, to have an important role in these patients and it is important to maximize its efficacy while minimizing toxicity to optimize outcomes. This review examines current HR-positive/HER2-negative MBC clinical guidelines and addresses key questions around the use of chemotherapy in the face of emerging therapeutic options. Specifically, the indications for chemotherapy in patients with HR-positive/HER2-negative MBC and the choice of optimal chemotherapy are discussed.


Assuntos
Antineoplásicos , Neoplasias da Mama , Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/patologia , Feminino , Humanos , Metástase Neoplásica , Receptor ErbB-2/metabolismo
9.
J Clin Oncol ; 40(25): 2946-2956, 2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-35763704

RESUMO

PURPOSE: Combining standard of care (pertuzumab-trastuzumab [PH], chemotherapy) with cancer immunotherapy may potentiate antitumor immunity, cytotoxic activity, and patient outcomes in high-risk, human epidermal growth factor receptor 2 (HER2)-positive early breast cancer. We report the phase III IMpassion050 primary analysis of neoadjuvant atezolizumab, PH, and chemotherapy in these patients. METHODS: Patients with a primary tumor of > 2 cm and histologically confirmed, positive lymph node status (T2-4, N1-3, M0) were randomly assigned 1:1 to atezolizumab/placebo with dose-dense doxorubicin/cyclophosphamide, followed by paclitaxel, and PH. After surgery, patients were to continue atezolizumab/placebo and PH (total: 1 year of HER2-targeted therapy); those with residual disease could switch to ado-trastuzumab emtansine with atezolizumab/placebo. Coprimary efficacy end points were pathologic complete response (pCR; ypT0/is ypN0) rates in intention-to-treat (ITT) and programmed cell death-ligand 1 (PD-L1)-positive populations. RESULTS: At clinical cutoff (February 5, 2021), pCR rates in the placebo and atezolizumab groups in the ITT populations were 62.7% (n = 143/228) and 62.4% (n = 141/226), respectively (difference -0.33%; 95% CI, -9.2 to 8.6; P = .9551). The pCR rates in the placebo and atezolizumab groups in patients with PD-L1-positive tumors were 72.5% (n = 79/109) and 64.2% (n = 70/109), respectively (difference -8.26%; 95% CI, -20.6 to 4.0; P = .1846). Grade 3-4 and serious adverse events were more frequent in the atezolizumab versus placebo group. Five grade 5 adverse events occurred (four neoadjuvant, one adjuvant; two assigned to study treatment), all with atezolizumab. Overall, the safety profile was consistent with that of atezolizumab in other combination studies. CONCLUSION: Atezolizumab with neoadjuvant dose-dense doxorubicin/cyclophosphamide-paclitaxel and PH for high-risk, HER2-positive early breast cancer did not increase pCR rates versus placebo in the ITT or PD-L1-positive populations. PH and chemotherapy remains standard of care; longer follow-up may help to inform the long-term impact of atezolizumab.


Assuntos
Neoplasias da Mama , Terapia Neoadjuvante , Anticorpos Monoclonais Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Antígeno B7-H1/uso terapêutico , Neoplasias da Mama/patologia , Ciclofosfamida , Doxorrubicina , Feminino , Humanos , Terapia Neoadjuvante/efeitos adversos , Paclitaxel , Receptor ErbB-2/metabolismo , Trastuzumab , Resultado do Tratamento
10.
ACS Appl Mater Interfaces ; 7(49): 27197-205, 2015 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-26584239

RESUMO

It has been shown that treatment with titanium dioxide nanoparticles (TiO2 NPs) combined with near-ultraviolet (UV-A) irradiation or in certain dark conditions reduced the numbers of various microorganisms, but the mechanism of this effect remains unclear. In this study to further clarify the mechanism of the antibacterial effect of TiO2 NPs the physiological state of E. coli K12 cells was estimated after incubation with the NPs (0.2 g/L) for different periods of time, with or without UV-A irradiation. Cell incubation with TiO2 NPs, combined or not combined with UV-A irradiation, showed that inactive cells were located only within cell aggregates formed after incubation with TiO2 NPs and that the larger the aggregate, the greater the number of such cells. When the formation of large aggregates was prevented, exposure to NPs under UV-A irradiation failed to result in cell inactivation. A comparative analysis of fluorescence and optical microscopic images of the same aggregates showed that the location of inactivated cells coincided with the zone of increased optical density within the aggregate. After treatment with TiO2 NPs under UV-A for 30, 60, or 120 min cells within the aggregates were the first to be inactivated. Cells on which NPs irradiated more strongly (at the periphery of large aggregates and single) remained active for a longer time than cells within the aggregates. As the time of treatment increased, so did the degree of cell compaction, with some zones of the aggregates eventually transforming into an acellular mass. After UV-A irradiation the cell aggregates spontaneously moved toward each other and gradually fused into larger structures, indicating that such exposure enhanced mutual attraction of cells treated with the NPs. Present study provides evidence for hypothesis that bacterial cells covered with TiO2 NPs are inactivated due to their mutual attraction and consequent compression.


Assuntos
Escherichia coli K12/efeitos dos fármacos , Nanopartículas/química , Titânio/farmacologia , DNA Bacteriano/efeitos dos fármacos , DNA Bacteriano/genética
11.
Colloids Surf B Biointerfaces ; 97: 240-7, 2012 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-22595541

RESUMO

TiO(2) nanoparticles (NPs) activated by UV irradiation are known to have a bactericidal effect. In this study we report the details of TiO(2) NPs influence on the colony-forming capacity of E. coli in the dark at pH 4.0-4.5. At this pH the bacterial cells are negatively charged and TiO(2) NPs present a positive charge. A 60 min contact between E. coli with TiO(2) at concentrations of 0.02-0.2 mg/mL led to a reduction of E. coli cell number from 10(8) to 10(4)CFU/mL. After the reduction the system remains unchanged during the subsequent incubation. The observed reduction was a function on the initial E. coli concentration. In the presence of 0.04 mg/mL TiO(2) the colony-forming units (CFU) reduction after 60 min was of four-five orders of magnitude when the initial concentration was 10(8) cells/mL. But when starting with an E. coli concentration of 10(7) cells/mL the cell number reduction was less than one order of magnitude. Less than one order of magnitude cell number reduction was also observed for suspensions of E. coli 10(8) cells/mL and 0.002 mg/mL of TiO(2). The bacteria number reduction was always accompanied by the formation of cell aggregates. During cell incubation with TiO(2), the pH of the suspension increased, but did not reach the TiO(2) isoelectric point (IEP). E. coli cells stained with the fluorescent dye acridine orange (AO) showed that the fluorescence of single cells remained unchanged after incubation in the presence of TiO(2). The color change of fluorescence was revealed only in aggregated cells. This suggests changes in the physiologic state of E. coli incorporated into the aggregates. Aggregates of E. coli occur due to the electrostatic interaction between TiO(2) NPs and the bacterial cell surface. A hypothesis is suggested in this study to explain the CFU reduction and the retention of a certain irreducible number of cells capable of further division in the suspension in the presence of TiO(2) in the dark.


Assuntos
Escherichia coli/efeitos dos fármacos , Nanopartículas/química , Titânio/química , Antibacterianos/química , Antibacterianos/farmacologia , Escherichia coli/citologia , Titânio/farmacologia , Raios Ultravioleta
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