RESUMEN
Recent advancements in particle design are common in reversed-phase liquid chromatography (RPLC), but in chiral separations their use is still sporadic in commercially available chiral stationary phases (CSPs). Due to reported lower mass transfer resistance, they might be a promising opportunity to increase efficiency and reduce time of analysis since the relatively higher mass transfer resistance term of CSPs caused by slow adsorption-desorption kinetics is the most performance-limiting factor in enantioselective chromatography. This study was dedicated to the evaluation of new support materials for tert-butylcarbamoylquinine (tBuCQN) based CSP to provide highly efficient and fast enantioseparations. As the main focus of this study, the chiral selector tBuCQN was immobilized on sub-2 µm fully porous particles (FPPs) and 2.7 µm superficially porous particles (SPPs) and their column performance in enantioseparation was evaluated in comparison to 5 µm FPPs by van Deemter and Knox analyses as well as kinetic plots using racemic Fmoc-Phe. Both new particle types outperformed the 5 µm FPP benchmark in terms of speed and efficiency, with wider pore materials (160 or 200 Å) being advantageous (over 90 or 120 Å). Basically decisive for the performance gain was the 10-times smaller mass transfer resistance. Furthermore, 2.7 µm 160 Å SPPs outperformed their fully porous sub-2 µm 120 Å counterpart (HminR = 4.64 µm vs. HminR = 8.94 µm) due to various parameters affording reduced plate height h of 1.7. Caused by the inaccessible core, separations were about 2-times faster. Packing of 2.7 µm core-shell particles provided a very homogeneous column bed, and, owing to its higher permeability, the column backpressure was much lower. It enables packing of longer columns providing theoretically separation efficiencies of up to 106 plates per m (as indicated by kinetic plots) and versatile use without the necessity of UHPLC systems. Investigating the effect of particle size reduction (FPPs: 5 µm, 3 µm, 1.7 µm; SPPs: 2.7 µm, 2 µm) and wider pores (FPPs: 120 Å, 200 Å; SPPs: 90 Å, 160 Å), a significantly reduced mass transfer resistance was the driving force for performance gain. Individual contributions of peak dispersion were deconvoluted for 5 µm FPP CSP and confirmed that slow adsorption-desorption kinetics is the most significant contribution to peak broadening in this chromatographic system.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Cromatografía por Intercambio Iónico/métodos , Tamaño de la Partícula , Adsorción , Aniones , Cromatografía de Fase Inversa , Cinética , Peso Molecular , PorosidadRESUMEN
A new platform technology for the preparation of stable chiral stationary phases was successfully optimized. The chiral selector tert-butylcarbamoylquinine was firstly covalently connected to the polymer poly(3-mercaptopropyl)methylsiloxane by thiol-ene click reaction. Secondly, the quinine carbamate functionalized polysiloxane conjugate was coated onto the surface of vinyl modified silica particles and cross-linked via thiol-ene click reaction. The amount of polysiloxane, chiral selector, radical initiator, reaction solvent (chloroform and methanol), reaction time, and pore size of the supporting silica particles were varied and systematically optimized in terms of achievable plate numbers while maintaining simultaneously enantioselectivity. The optimization was based on elemental analysis data, chromatographic results, and H/u-curves (Van Deemter) of the resultant chiral stationary phases. The results suggest that better chromatographic efficiency (higher plate numbers) at equal enantioselectivity can be achieved with methanol (a poor solvent for the polysiloxane that is dispersed rather than dissolved) and a lower film thickness of quinine carbamate functionalized polysiloxane. In this study, chiral stationary phases based on 100 Å silica slightly outperformed 200 Å silica particles (each 5 µm). The optimized two step material exhibited significantly reduced mass transfer resistance compared to the one step material and equal performance as a brush-type chiral stationary phase.
RESUMEN
Despite mounting epidemiological evidence suggesting an inverse association between recreational physical activity and cancer risk, evidence associated with head and neck cancer is scant. We conducted a case-control analysis to examine the associations of lifetime physical inactivity with the risk of head and neck squamous cell carcinoma (HNSCC). We utilized data from the Patient Epidemiology Data System at Roswell Park Cancer Institute (RPCI). Participants included 246 patients with HNSCC and 504 cancer-free controls who received medical services at RPCI between 1990 and 1998. Participants were considered physically inactive if they did not participate in any regular, weekly recreational physical activity throughout their lifetime, prior to diagnosis. Multivariate logistic regression models were utilized to estimate odds ratios (OR) and 95% confidence intervals (CI) representing the association between lifetime physical inactivity and HNSCC risk. We observed a significant positive association between recreational physical inactivity and HNSCC risk (OR = 2.73, 95% CI 1.87-3.99, p < 0.001). In subgroup analyses by body mass index (BMI) (underweight/normal-weight: OR = 3.40, 95% CI 1.89-6.12, p < 0.001; overweight/obese: OR = 2.40, 95% CI 1.43-4.02, p < 0.001) and smoking status (former smoker: OR = 3.12, 95% CI 1.89-5.14, p < 0.001; never smoker: OR = 2.71, 95% CI 1.21-6.05, p = 0.020; current smoker: OR = 1.61, 95% CI 0.66-3.95, p = 0.300), significant positive associations were also observed. Results of the current analyses suggest that lifetime physical inactivity associates with HNSCC independent of BMI. In addition, physical inactivity may be a modifiable risk factor among never smokers. These data add to the growing body of evidence suggesting that physical inactivity may be an independent risk factor for cancer.
Asunto(s)
Carcinoma de Células Escamosas , Ejercicio Físico/fisiología , Neoplasias de Cabeza y Cuello , Obesidad , Adulto , Anciano , Índice de Masa Corporal , Carcinoma de Células Escamosas/epidemiología , Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/fisiopatología , Estudios de Casos y Controles , Femenino , Neoplasias de Cabeza y Cuello/epidemiología , Neoplasias de Cabeza y Cuello/patología , Neoplasias de Cabeza y Cuello/fisiopatología , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Obesidad/diagnóstico , Obesidad/epidemiología , Obesidad/fisiopatología , Oportunidad Relativa , Recreación/fisiología , Medición de Riesgo , Factores de Riesgo , Fumar/epidemiología , Carcinoma de Células Escamosas de Cabeza y Cuello , Estadística como Asunto , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVES: Recreational physical inactivity has been gaining recognition as an independent epidemiological exposure of interest in relation to cancer endpoints due to evidence suggesting that it may associate with cancer independent of obesity. In the current analyses, we examined the associations of lifetime recreational physical inactivity with renal and bladder cancer risk. METHODS: In this hospital-based case-control study, we identified N=160 renal cancer patients, N=208 bladder cancer patients, and N=766 age frequency-matched controls without cancer. Participants self-reporting never participating in any regular/weekly recreational physical activity throughout their lifetime were classified as physically inactive. Utilizing unconditional multivariable logistic regression analyses, we estimated odds ratios and 95% confidence intervals to represent the associations between lifetime physical inactivity and renal and bladder cancer risk. RESULTS: In multivariable logistic regression models, we observed significant positive associations between lifetime recreational physical inactivity and renal cancer and bladder cancer risk: odds ratio=1.77 (95% CI: 1.10-2.85) and odds ratio=1.73 (95% CI: 1.13-2.63), respectively. Similar associations also persisted among individuals who were not obese for both renal and bladder cancer: odds ratio=1.75 (95% CI: 1.03-2.98) and odds ratio=1.70 (95% CI: 1.08-2.69), respectively. CONCLUSIONS: In this case-control study, we observed evidence of a positive association between renal and bladder cancer with lifetime recreational physical inactivity. These data add to the growing body of evidence suggesting that physical inactivity may be an important independent risk factor for cancer. However, additional studies using a larger sample and prospectively collected data are needed to substantiate the current findings.
Asunto(s)
Neoplasias Renales/epidemiología , Conducta Sedentaria , Neoplasias de la Vejiga Urinaria/epidemiología , Anciano , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Actividad Motora , New York/epidemiología , Obesidad/epidemiología , Oportunidad Relativa , Sistema de Registros , RiesgoRESUMEN
OBJECTIVE: There is a mounting body of evidence demonstrating higher percentages of regulatory T (Treg) cells in the peripheral blood of patients with cancer in comparison to healthy controls, but there is a paucity of epidemiological literature characterizing circulating Treg cells among patients with epithelial ovarian cancer (EOC). To investigate the role of peripheral Treg cells in ovarian neoplasms, we conducted a case-control study to characterize circulating concentrations of Treg cells among patients with EOC, women with benign ovarian conditions, and healthy controls without a history of cancer. MATERIALS AND METHODS: Participants were identified for inclusion due to their participation in the Data Bank and BioRepository program at Roswell Park Cancer Institute in Buffalo, NY. Patients included 71 women with a primary diagnosis of EOC and 195 women with a diagnosis of benign ovarian conditions. Controls included 101 age- and race-matched women without a history of cancer. Nonfasting, pretreatment peripheral blood levels of CD3+CD4+CD25+FOXP3+ Treg cells were measured using flow cytometric analyses and expressed as a percentage of total CD3+ cells and as a percentage of total CD3+CD4+ cells. RESULTS: Compared to healthy controls and women with benign ovarian conditions, patients with EOC had significantly higher frequency of Treg cells (P < 0.04). In multivariable logistic regression analyses using Treg frequency expressed as a percentage of CD+3 cells, we observed a significant positive association between Treg cell percentage and EOC risk, with each 1% increase associated with a 37% increased risk of EOC (odds ratio, 1.37; 95% confidence interval, 1.04-1.80). We observed a similar trend when Treg frequency was expressed as a percentage of CD3+CD+4 cells (odds ratio, 1.22; 95% confidence interval, 0.99-1.49). CONCLUSIONS: The current study provides support that peripheral Treg cell frequency is elevated in patients with EOC in comparison to women with benign ovarian conditions and healthy controls.
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Neoplasias Glandulares y Epiteliales/sangre , Neoplasias Ováricas/sangre , Linfocitos T Reguladores/patología , Factores de Edad , Carcinoma Epitelial de Ovario , Estudios de Casos y Controles , Femenino , Humanos , Persona de Mediana Edad , Neoplasias Glandulares y Epiteliales/inmunología , Neoplasias Ováricas/inmunología , Linfocitos T Reguladores/inmunologíaRESUMEN
OBJECTIVE: In this study, we investigated whether physical inactivity was associated with risk of cervical cancer in women treated at an American cancer hospital. METHODS: This case-control study included 128 patients with cervical cancer and 512 controls matched on age. Controls were women suspected of having but not ultimately diagnosed with a neoplasm. Physical inactivity was defined in accordance with the 2008 Physical Activity Guidelines for Americans. Thus, participants reporting, on average, no moderate or vigorous recreational physical activity were classified as inactive. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Compared with noncancer controls, those with cervical cancer had significantly increased odds of reporting abstinence from recreational physical activity (OR, 2.43; 95% CI, 1.56-3.80). No association was noted between occupational-related physical inactivity and cervical cancer (OR, 0.88; 95% CI, 0.58-1.36). CONCLUSIONS: Our findings suggest that abstinence from regular recreational physical activity is associated with increased odds of cervical cancer. To our knowledge, this is the first US-based study examining these associations. Given the 2008 Physical Activity Guidelines for Americans, this study has identified yet another potential public health benefit to regular physical activity. Further investigation is needed using a larger sample and prospectively collected data to characterize dose of activity to mitigate risk and the optimal window of susceptibility.
Asunto(s)
Ejercicio Físico , Neoplasias del Cuello Uterino/epidemiología , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Medición de Riesgo , Adulto JovenRESUMEN
OBJECTIVE: In this study, we investigated whether regular use of aspirin or acetaminophen was associated with risk of cervical cancer in women treated at an American cancer hospital. METHODS: This case-control study included 328 patients with cervical cancer and 1,312 controls matched on age and decade enrolled. Controls were women suspected of having but not ultimately diagnosed with a neoplasm. Analgesic use was defined as regular (at least once per week for ≥6 months), frequent (≥7 tablets/week), very long term (≥11 years), or frequent, long term (≥7 tablets per week for ≥5 years). RESULTS: Compared to nonusers, frequent aspirin use was associated with decreased odds of cervical cancer (odds ratio, 0.53; 95% confidence interval, 0.29-0.97). A slightly larger association was observed with frequent, long-term use of aspirin (odds ratio, 0.46; 95% confidence interval, 0.22-0.95). Acetaminophen use was not associated with the risk of cervical cancer. CONCLUSIONS: Our findings suggest that frequent and frequent, long-term use of aspirin is associated with decreased odds of cervical cancer. To our knowledge, this is the first US-based study examining these associations. Given the widespread use of nonsteroidal anti-inflammatory drugs and acetaminophen worldwide, further investigations of the possible role of analgesics in cervical cancer, using a larger sample size with better-defined dosing regimens, are warranted.